Publications OUCRU-Nepal

Näsström E, Jonsson P, Johansson A, Dongol S, Karkey A, Basnyat B, Tran Vu Thieu N, Trinh Van T, Thwaites GE, Antti H, Baker S. 2018. Diagnostic metabolite biomarkers of chronic typhoid carriage. PLoS Negl Trop Dis, 12 (1), pp. e0006215. | Show Abstract | Read more

BACKGROUND: Salmonella Typhi and Salmonella Paratyphi A are the agents of enteric (typhoid) fever; both can establish chronic carriage in the gallbladder. Chronic Salmonella carriers are typically asymptomatic, intermittently shedding bacteria in the feces, and contributing to disease transmission. Detecting chronic carriers is of public health relevance in areas where enteric fever is endemic, but there are no routinely used methods for prospectively identifying those carrying Salmonella in their gallbladder. METHODOLOGY/PRINCIPAL FINDINGS: Here we aimed to identify biomarkers of Salmonella carriage using metabolite profiling. We performed metabolite profiling on plasma from Nepali patients undergoing cholecystectomy with confirmed S. Typhi or S. Paratyphi A gallbladder carriage (and non-carriage controls) using two-dimensional gas chromatography coupled with time-of-flight mass spectrometry (GCxGC-TOFMS) and supervised pattern recognition modeling. We were able to significantly discriminate Salmonella carriage samples from non-carriage control samples. We were also able to detect differential signatures between S. Typhi and S. Paratyphi A carriers. We additionally compared carriage metabolite profiles with profiles generated during acute infection; these data revealed substantial heterogeneity between metabolites associated with acute enteric fever and chronic carriage. Lastly, we found that Salmonella carriers could be significantly distinguished from non-carriage controls using only five metabolites, indicating the potential of these metabolites as diagnostic markers for detecting chronic Salmonella carriers. CONCLUSIONS/SIGNIFICANCE: Our novel approach has highlighted the potential of using metabolomics to search for diagnostic markers of chronic Salmonella carriage. We suggest further epidemiological investigations of these potential biomarkers in alternative endemic enteric fever settings.

Baniya S, Basnyat B. 2018. Mismanagement of Severe Altitude Illness in a Tertiary Hospital in Nepal: A Cautionary Tale. Wilderness Environ Med, | Read more

Parati G, Agostoni P, Basnyat B, Bilo G, Brugger H, Coca A, Festi L, Giardini G, Lironcurti A, Luks AM et al. 2018. Clinical recommendations for high altitude exposure of individuals with pre-existing cardiovascular conditions. Eur Heart J, | Read more

Thapa SS, Basnyat B. 2018. Common Bite-Bizarre Rash. Wilderness Environ Med, | Read more

Shrestha P, Shakya M, Caws M, Shrestha S, Karki B, Shrestha S, Karki DB, Maharjan B, Shrestha B, Arjyal A et al. 2018. Tuberculosis in Staff and Students of Patan Hospital. J Nepal Health Res Counc, 15 (3), pp. 268-274. | Show Abstract

BACKGROUND: There is a high risk of occupational exposure to tuberculosis among healthcare workers in endemic countries. Regular screening for tuberculosis among healthcare workers is not carried out in Nepal. Infection control measures are also not routinely implemented. The aim of this study was to determine the prevalence of active tuberculosis among staff/students at Patan Hospital. METHODS: Participants were given a self-administered questionnaire and invited to undergo chest radiography. Cases were scored and reviewed based on predetermined criteria, and presumptive tuberculosis cases were invited to undergo sputum smear and culture. Participants were categorized according to the extent of patient contact and asked about history of tuberculosis medication. RESULTS: Among 560 participants, 76.8% had direct contact with patients. Fifty-eight (10.4%) gave history of cough >2 weeks. Based on symptom history and chest radiography, 20.0% (n=112) cases were reviewed, and 12.5% (n=14) of those reviewed had sputum tested for acid-fast bacilli. One participant had culture-positive tuberculosis. Fifty participants (8.9%) reported tuberculosis in the past, among which 42.0% (n=21) occurred after employment at Patan Hospital and 42.0% before joining Patan Hospital. Security staff, radiology technicians and ward cleaning staff had the highest proportion of cases with a history of tuberculosis.History of tuberculosis medication had no relation with age, sex, education, body mass index and smoking.The incidence rate of tuberculosis at Patan Hospital was 3.6 per 1000 person-years. CONCLUSIONS: Overall incidence of tuberculosis among healthcare workers is noteworthy. However, this study suggests when symptomatic tuberculosis occurs in healthcare worker at Patan Hospital, it is diagnosed and there is not a large pool of undiagnosed tuberculosis.

Reisman J, Deonarain D, Basnyat B. 2017. Impact of a Newly Constructed Motor Vehicle Road on Altitude Illness in the Nepal Himalayas. Wilderness Environ Med, 28 (4), pp. 332-338. | Citations: 1 (Web of Science Lite) | Show Abstract | Read more

OBJECTIVE: This study investigated the impact that motor vehicle travel along a newly constructed road has on altitude illness (including acute mountain sickness, high-altitude cerebral edema, and high-altitude pulmonary edema). The new road from Besisahar (760 m) to Manang (3540 m) in Nepal was completed in December 2014. METHODS: We enrolled all patients diagnosed with altitude illness at the Himalayan Rescue Association Manang clinic in fall 2016. Phi coefficients were calculated to test for an association between Nepali ethnicity and rapid ascent by motor vehicle. A retrospective review looked at all patients with altitude illness from fall (September-November) 2010 to spring (February-May) 2016. RESULTS: In fall 2016, more than half (54%) of patients with altitude illness traveled to Manang by motor vehicle, and one-third (33%) reached Manang from low altitude (Besisahar) in less than 48 hours. Nepali nationality had a significant association with motor vehicle travel (phi +0.69, P < .0001) as well as with rapid ascent to Manang (phi +0.72, P < .0001). Compared to previous seasons, fall 2016 saw the most patients diagnosed with altitude illness. The proportion of people with altitude illness who traveled by vehicle and reached Manang in less than 48 hours was significantly greater than the proportion prior to completion of the road (P < .0001 for both). CONCLUSIONS: Rapid ascent by the newly constructed road from Besisahar to Manang appears to be related to a significant increase in the number of patients with all forms of altitude illness, especially among Nepalis. The authors believe that educational interventions emphasizing prevention are urgently needed.

Basnyat B, Hofmeyr R, Tölken G, De Decker R. 2017. Acute high-altitude illness. S Afr Med J, 107 (12), pp. 1047-1048. | Show Abstract | Read more

Letter by Basnyat on article by Hofmeyr et al. (Hofmeyr R, Tölken G, De Decker R. Acute high-altitude illness. S Afr J Med 2017;107(7):556-561. https://doi.org/10.7196/SAMJ.2017.v107i7.12612); and response by Hofmeyr et al.

Kanaan NC, Peterson AL, Pun M, Thapa GB, Tiwari A, Basyal B, Holck PS, Starling J, Freeman TF, Gehner JR et al. 2017. In Response to Ibuprofen vs Acetaminophen in AMS Prevention by Kanaan et al Reply WILDERNESS & ENVIRONMENTAL MEDICINE, 28 (4), pp. 385-387.

Janocha AJ, Comhair SAA, Basnyat B, Neupane M, Gebremedhin A, Khan A, Ricci KS, Zhang R, Erzurum SC, Beall CM. 2017. Antioxidant defense and oxidative damage vary widely among high-altitude residents. Am J Hum Biol, 29 (6), pp. e23039-e23039. | Citations: 1 (Scopus) | Show Abstract | Read more

OBJECTIVES: People living at high altitude experience unavoidable low oxygen levels (hypoxia). While acute hypoxia causes an increase in oxidative stress and damage despite higher antioxidant activity, the consequences of chronic hypoxia are poorly understood. The aim of the present study is to assess antioxidant activity and oxidative damage in high-altitude natives and upward migrants. METHODS: Individuals from two indigenous high-altitude populations (Amhara, n = 39), (Sherpa, n = 34), one multigenerational high-altitude population (Oromo, n = 42), one upward migrant population (Nepali, n = 12), and two low-altitude reference populations (Amhara, n = 29; Oromo, n = 18) provided plasma for measurement of superoxide dismutase (SOD) activity as a marker of antioxidant capacity, and urine for measurement of 8-hydroxy-2'-deoxyguanosine (8-OHdG) as a marker of DNA oxidative damage. RESULTS: High-altitude Amhara and Sherpa had the highest SOD activity, while highland Oromo and Nepalis had the lowest among high-altitude populations. High-altitude Amhara had the lowest DNA damage, Sherpa intermediate levels, and high-altitude Oromo had the highest. CONCLUSIONS: High-altitude residence alone does not associate with high antioxidant defenses; residence length appears to be influential. The single-generation upward migrant sample had the lowest defense and nearly the highest DNA damage. The two high-altitude resident samples with millennia of residence had higher defenses than the two with multiple or single generations of residence.

Zellweger RM, Basnyat B, Shrestha P, Prajapati KG, Dongol S, Sharma PK, Koirala S, Darton TC, Dolecek C, Thompson CN et al. 2017. A 23-year retrospective investigation of Salmonella Typhi and Salmonella Paratyphi isolated in a tertiary Kathmandu hospital. PLoS Negl Trop Dis, 11 (11), pp. e0006051. | Show Abstract | Read more

BACKGROUND: Salmonella serovars Typhi (S. Typhi) and Paratyphi A (S. Paratyphi A), the causative agents of enteric fever, have been routinely isolated organisms from the blood of febrile patients in the Kathmandu Valley since the early 1990s. Susceptibility against commonly used antimicrobials for treating enteric fever has gradually changed throughout South Asia since this time, posing serious treatment challenges. Here, we aimed to longitudinally describe trends in the isolation of Salmonella enterica and assess changes in their antimicrobial susceptibility in Kathmandu over a 23-year period. METHODS: We conducted a retrospective analysis of standardised microbiological data from April 1992 to December 2014 at a single healthcare facility in Kathmandu, examining time trends of Salmonella-associated bacteraemia and the corresponding antimicrobial susceptibility profiles of the isolated organisms. RESULTS: Over 23 years there were 30,353 positive blood cultures. Salmonella enterica accounted for 65.4% (19,857/30,353) of all the bacteria positive blood cultures. S. Typhi and S. Paratyphi A were the dominant serovars, constituting 68.5% (13,592/19,857) and 30.5% (6,057/19,857) of all isolated Salmonellae. We observed (i) a peak in the number of Salmonella-positive cultures in 2002, a year of heavy rainfall and flooding in the Kathmandu Valley, followed by a decline toward pre-flood baseline by 2014, (ii) an increase in the proportion of S. Paratyphi in all Salmonella-positive cultures between 1992 and 2014, (iii) a decrease in the prevalence of MDR for both S. Typhi and S. Paratyphi, and (iv) a recent increase in fluoroquinolone non-susceptibility in both S. Typhi and S. Paratyphi isolates. CONCLUSIONS: Our work describes significant changes in the epidemiology of Salmonella enterica in the Kathmandu Valley during the last quarter of a century. We highlight the need to examine current treatment protocols for enteric fever and suggest a change from fluoroquinolone monotherapy to combination therapies of macrolides or cephalosporins along with older first-line antimicrobials that have regained their efficacy.

Darton TC, Jones C, Dongol S, Voysey M, Blohmke CJ, Shrestha R, Karkey A, Shakya M, Arjyal A, Waddington CS et al. 2017. Assessment and Translation of the Antibody-in-Lymphocyte Supernatant (ALS) Assay to Improve the Diagnosis of Enteric Fever in Two Controlled Human Infection Models and an Endemic Area of Nepal. Front Microbiol, 8 (OCT), pp. 2031. | Show Abstract | Read more

New diagnostic tests for enteric fever are urgently needed to assist with timely antimicrobial treatment of patients and to measure the efficacy of prevention measures such as vaccination. In a novel translational approach, here we use two recently developed controlled human infection models (CHIM) of enteric fever to evaluate an antibody-in-lymphocyte supernatant (ALS) assay, which can detect recent IgA antibody production by circulating B cells inex vivomononuclear cell culture. We calculated the discriminative ability of the ALS assay to distinguish diagnosed cases in the two CHIM studies in Oxford, prior to evaluating blood culture-confirmed diagnoses of patients presenting with fever to hospital in an endemic areas of Kathmandu, Nepal. Antibody responses to membrane preparations and lipopolysaccharide provided good sensitivity (>90%) for diagnosing systemic infection after oral challenge withSalmonellaTyphi orS. Paratyphi A. Assay specificity was moderate (~60%) due to imperfect sensitivity of blood culture as the reference standard and likely unrecognized subclinical infection. These findings were augmented through the translation of the assay into the endemic setting in Nepal. Anti-MP IgA responses again exhibited good sensitivity (86%) but poor specificity (51%) for detecting blood culture-confirmed enteric fever cases (ROC AUC 0.79, 95%CI 0.70-0.88). Patients with anti-MP IgA ALS titers in the upper quartile exhibited a clinical syndrome synonymous with enteric fever. While better reference standards are need to assess enteric fever diagnostics, routine use of this ALS assay could be used to rule out infection and has the potential to double the laboratory detection rate of enteric fever in this setting over blood culture alone.

Pokharel S, Basnyat B, Arjyal A, Mahat SP, Kc RK, Bhuju A, Poudyal B, Kestelyn E, Shrestha R, Phuong DNT et al. 2017. Co-trimoxazole versus azithromycin for the treatment of undifferentiated febrile illness in Nepal: study protocol for a randomized controlled trial. Trials, 18 (1), pp. 450. | Citations: 1 (Scopus) | Show Abstract | Read more

BACKGROUND: Undifferentiated febrile illness (UFI) includes typhoid and typhus fevers and generally designates fever without any localizing signs. UFI is a great therapeutic challenge in countries like Nepal because of the lack of available point-of-care, rapid diagnostic tests. Often patients are empirically treated as presumed enteric fever. Due to the development of high-level resistance to traditionally used fluoroquinolones against enteric fever, azithromycin is now commonly used to treat enteric fever/UFI. The re-emergence of susceptibility of Salmonella typhi to co-trimoxazole makes it a promising oral treatment for UFIs in general. We present a protocol of a randomized controlled trial of azithromycin versus co-trimoxazole for the treatment of UFI. METHODS/DESIGN: This is a parallel-group, double-blind, 1:1, randomized controlled trial of co-trimoxazole versus azithromycin for the treatment of UFI in Nepal. Participants will be patients aged 2 to 65 years, presenting with fever without clear focus for at least 4 days, complying with other study criteria and willing to provide written informed consent. Patients will be randomized either to azithromycin 20 mg/kg/day (maximum 1000 mg/day) in a single daily dose and an identical placebo or co-trimoxazole 60 mg/kg/day (maximum 3000 mg/day) in two divided doses for 7 days. Patients will be followed up with twice-daily telephone calls for 7 days or for at least 48 h after they become afebrile, whichever is later; by home visits on days 2 and 4 of treatment; and by hospital visits on days 7, 14, 28 and 63. The endpoints will be fever clearance time, treatment failure, time to treatment failure, and adverse events. The estimated sample size is 330. The primary analysis population will be all the randomized population and subanalysis will be repeated on patients with blood culture-confirmed enteric fever and culture-negative patients. DISCUSSION: Both azithromycin and co-trimoxazole are available in Nepal and are extensively used in the treatment of UFI. Therefore, it is important to know the better orally administered antimicrobial to treat enteric fever and other UFIs especially against the background of fluoroquinolone-resistant enteric fever. TRIAL REGISTRATION: ClinicalTrials.gov, ID: NCT02773407 . Registered on 5 May 2016.

Darton TC, Baker S, Randall A, Dongol S, Karkey A, Voysey M, Carter MJ, Jones C, Trappl K, Pablo J et al. 2017. Identification of Novel Serodiagnostic Signatures of Typhoid Fever Using a Salmonella Proteome Array. Front Microbiol, 8 (SEP), pp. 1794. | Show Abstract | Read more

Current diagnostic tests for typhoid fever, the disease caused by Salmonella Typhi, are poor. We aimed to identify serodiagnostic signatures of typhoid fever by assessing microarray signals to 4,445 S. Typhi antigens in sera from 41 participants challenged with oral S. Typhi. We found broad, heterogeneous antibody responses with increasing IgM/IgA signals at diagnosis. In down-selected 250-antigen arrays we validated responses in a second challenge cohort (n = 30), and selected diagnostic signatures using machine learning and multivariable modeling. In four models containing responses to antigens including flagellin, OmpA, HlyE, sipC, and LPS, multi-antigen signatures discriminated typhoid (n = 100) from other febrile bacteremia (n = 52) in Nepal. These models contained combinatorial IgM, IgA, and IgG responses to 5 antigens (ROC AUC, 0.67 and 0.71) or 3 antigens (0.87), although IgA responses to LPS also performed well (0.88). Using a novel systematic approach we have identified and validated optimal serological diagnostic signatures of typhoid fever.

Baniya S, Holden C, Basnyat B. 2017. Reentry High Altitude Pulmonary Edema in the Himalayas. High Alt Med Biol, 18 (4), pp. 425-427. | Show Abstract | Read more

Baniya, Santosh, Christopher Holden, and Buddha Basnyat. Reentry high altitude pulmonary edema in the Himalayas. High Alt Med Biol. 18:425-427, 2017.-Reentry high altitude pulmonary edema (HAPE), a subset of HAPE, is a well recognized, life-threatening illness documented almost exclusively in the North and South Americans, who live at high altitude (>2500 m) and return to their homes after a brief sojourn of days to months at lower altitude. This phenomenon has not been reported in Sherpas or other people of Tibetan origin in Nepal or India. And it has rarely been reported from Tibet. In this study we document a case of reentry HAPE in Manang region (3500 m) of Nepal in a 7-year-old Nepali boy of Tibetan ancestry who fell ill when he ascended to his village (Manang, 3500 m) from Besisahar (760 m) in 1 day in a motor vehicle after spending the winter (December to March) at Besisahar with his family. With more motorable road access to high altitude settlements in the Himalayas, reentry HAPE may need to be strongly considered by healthcare professionals in local residents of high altitude; otherwise life-threatening complications may ensue as in our case report.

Ujka K, Bruno RM, Bastiani L, Bernardi E, Sdringola P, Dikic N, Basyal B, Bhandari SS, Basnyat B, Cogo A, Pratali L. 2017. Relationship Between Occupational Physical Activity and Subclinical Vascular Damage in Moderate-Altitude Dwellers. High Alt Med Biol, 18 (3), pp. 249-257. | Show Abstract | Read more

Ujka, Kristian, Rosa Maria Bruno, Luca Bastiani, Eva Bernardi, Paolo Sdringola, Nenad Dikic, Bikash Basyal, Sanjeeb Sundarshan Bhandari, Buddha Basnyat, Annalisa Cogo, and Lorenza Pratali. Relationship between occupational physical activity and subclinical vascular damage in moderate-altitude dwellers. High Alt Med Biol. 18:249-257, 2017. BACKGROUND: Occupational physical activity (OPA) has been associated with increased cardiovascular (CV) events. The aim of this study was to investigate the association between OPA and markers of subclinical vascular damage among a moderate-altitude population living in the rural village of Chaurikharka (Nepal; 2600 m sea level). METHODS: Seventy-two individuals (age 42 ± 15 years, ranges 15-85 years, 23 men) were enrolled. Physical activity (PA) was evaluated using the International Physical Activity Questionnaire (IPAQ). Carotid-femoral pulse wave velocity (PWV), carotid ultrasound assessment, and flow-mediated dilation (FMD) were performed. RESULTS: OPA was 9860 ± 5385 Metabolic Equivalent of Task (MET)-minutes/week, representing 77% of total energy expenditure, with 97% of the population performing high-intensity PA. In the univariate analysis, OPA was significantly associated with PWV (β = 0.474, p = 0.001) and carotid stiffness (CS) (β = 0.29, p = 0.019). In the multivariate analysis, including age, sex, oxygen saturation, mean blood pressure, low-density lipoprotein (LDL), and OPA, OPA remained an independent predictor of PWV (β = 0.403, p = 0.001) but not of CS (β = 0.028, p = 0.8). OPA remained an independent predictor of PWV independently from the Framingham risk score (FRS). CONCLUSION: High-intensity OPA shows a positive, independent association with aortic stiffness in Himalayan moderate-altitude dwellers. This study suggests how vigorous OPA performed in moderate altitude may be a CV risk factor.

Keyes LE, Sallade TD, Duke C, Starling J, Sheets A, Pant S, Young DS, Twillman D, Regmi N, Phelan B et al. 2017. Blood Pressure and Altitude: An Observational Cohort Study of Hypertensive and Nonhypertensive Himalayan Trekkers in Nepal. High Alt Med Biol, 18 (3), pp. 267-277. | Show Abstract | Read more

Keyes, Linda E., Thomas Douglas Sallade, Charles Duke, Jennifer Starling, Alison Sheets, Sushil Pant, David S. Young, David Twillman, Nirajan Regmi, Benoit Phelan, Purshotam Paudel, Matthew McElwee, Luke Mather, Devlin Cole, Theodore McConnell, and Buddha Basnyat. Blood pressure and altitude: an observational cohort study of hypertensive and nonhypertensive Himalayan trekkers in Nepal. High Alt Med Biol. 18:267-277, 2017. OBJECTIVES: To determine how blood pressure (BP) changes with altitude in normotensive versus hypertensive trekkers. Secondary aims were to evaluate the prevalence of severe hypertension (BP ≥180/100 mmHg) and efficacy of different antihypertensive agents at high altitude. METHODS: This was an observational cohort study of resting and 24-hour ambulatory BP in normotensive and hypertensive trekkers at 2860, 3400, and 4300 m in Nepal. RESULTS: We enrolled 672 trekkers age 18 years and older, 60 with a prior diagnosis of hypertension. Mean systolic and diastolic BP did not change between altitudes in normotensive or hypertensive trekkers, but was higher in those with hypertension. However, there was large interindividual variability. At 3400 m, the majority (60%, n = 284) of normotensive participants had a BP within 10 mmHg of their BP at 2860 m, while 21% (n = 102) increased and 19% (n = 91) decreased. The pattern was similar between 3400 and 4300 m (64% [n = 202] no change, 21% [n = 65] increased, 15% [n = 46] decreased). BP decreased in a greater proportion of hypertensive trekkers versus normotensives (36% [n = 15] vs. 21% at 3400 m, p = 0.01 and 30% [n = 7] vs. 15% at 4300 m, p = 0.05). Severe hypertension occurred in both groups, but was asymptomatic. In a small subset of participants, 24-hour ambulatory BP monitoring showed that nocturnal BP decreased in normotensive (n = 4) and increased in hypertensive trekkers (n = 4). CONCLUSIONS: Most travelers, including those with well-controlled hypertension, can be reassured that their BP will remain relatively stable at high altitude. Although extremely elevated BP may be observed at high altitude in normotensive and hypertensive people, it is unlikely to be symptomatic. The ideal antihypertensive regimen at high altitude remains unclear.

Meiring JE, Gibani M, TyVAC Consortium Meeting Group:. 2017. The Typhoid Vaccine Acceleration Consortium (TyVAC): Vaccine effectiveness study designs: Accelerating the introduction of typhoid conjugate vaccines and reducing the global burden of enteric fever. Report from a meeting held on 26-27 October 2016, Oxford, UK. Vaccine, 35 (38), pp. 5081-5088. | Show Abstract | Read more

Typhoid fever is estimated to cause between 11.9-26.9 million infections globally each year with 129,000-216,510 deaths. Access to improved water sources have reduced disease incidence in parts of the world but the use of efficacious vaccines is seen as an important public health tool for countries with a high disease burden. A new generation of Vi typhoid conjugate vaccines (TCVs), licensed for use in young children and expected to provide longer lasting protection than previous vaccines, are now available. The WHO Strategic Advisory Group of Experts on Immunization (SAGE) has convened a working group to review the evidence on TCVs and produce an updated WHO position paper for all typhoid vaccines in 2018 that will inform Gavi, the Vaccine Alliance's future vaccine investment strategies for TCVs. The Typhoid Vaccine Acceleration Consortium (TyVAC) has been formed through a $36.9 million funding program from the Bill & Melinda Gates Foundation to accelerate the introduction of TCVs into Gavi-eligible countries. In October 2016, a meeting was held to initiate planning of TCV effectiveness studies that will provide the data required by policy makers and stakeholders to support decisions on TCV use in countries with a high typhoid burden. Discussion topics included (1) the latest evidence and data gaps in typhoid epidemiology; (2) WHO and Gavi methods and data requirements; (3) data on TCV efficacy; (4) cost effectiveness analysis for TCVs from mathematical models; (5) TCV delivery and effectiveness study design. Specifically, participants were asked to comment on study design in 3 sites for which population-based typhoid surveillance is underway. The conclusion of the meeting was that country-level decision making would best be informed by the respective selected sites in Africa and Asia vaccinating children aged from 9-months to 15-years-old, employing either an individual or cluster randomized design with design influenced by population characteristics, transmission dynamics, and statistical considerations.

Sharma P, Bhuju A, Tuladhar R, Parry CM, Basnyat B. 2017. Tubo-ovarian abscess infected by Salmonella typhi. BMJ Case Rep, 2017 pp. bcr-2017-221213-bcr-2017-221213. | Show Abstract | Read more

We report a case of a tubo-ovarian abscess infected with Salmonella enterica serotype typhi A 19-year-old Nepalese woman presented to a hospital in Kathmandu with lower abdominal pain, constipation, fever and a non-healing, suppurative surgical wound from an emergency caesarian section performed 2 months previously at 37 weeks of pregnancy. She also had an exploratory laparotomy for an appendix perforation with peritonitis at 25 weeks of gestation. Her wound infection did not respond to cloxacillin and she had an exploratory laparotomy, and a tubo-ovarian abscess was found from which S. typhi was isolated. She had a bilateral salpingo-oophorectomy and responded to 14 days of chloramphenicol. A tubo-ovarian abscess is a rare complication of enteric fever.

Jeong C, Peter BM, Basnyat B, Neupane M, Beall CM, Childs G, Craig SR, Novembre J, Di Rienzo A. 2017. Correction: A longitudinal cline characterizes the genetic structure of human populations in the Tibetan plateau. PLoS One, 12 (8), pp. e0183407. | Show Abstract | Read more

[This corrects the article DOI: 10.1371/journal.pone.0175885.].

Thapa SS, Basnyat B. 2017. Chronic Diarrhea in a Traveler: Cyclosporiasis. Am J Med, 130 (12), pp. e535-e536. | Read more

Darton TC, Meiring JE, Tonks S, Khan MA, Khanam F, Shakya M, Thindwa D, Baker S, Basnyat B, Clemens JD et al. 2017. The STRATAA study protocol: a programme to assess the burden of enteric fever in Bangladesh, Malawi and Nepal using prospective population census, passive surveillance, serological studies and healthcare utilisation surveys. BMJ Open, 7 (6), pp. e016283. | Citations: 1 (Web of Science Lite) | Show Abstract | Read more

INTRODUCTION: Invasive infections caused bySalmonella entericaserovar Typhi and Paratyphi A are estimated to account for 12-27 million febrile illness episodes worldwide annually. Determining the true burden of typhoidalSalmonellaeinfections is hindered by lack of population-based studies and adequate laboratory diagnostics.The Strategic Typhoid alliance across Africa and Asia study takes a systematic approach to measuring the age-stratified burden of clinical and subclinical disease caused by typhoidalSalmonellaeinfections at three high-incidence urban sites in Africa and Asia. We aim to explore the natural history ofSalmonellatransmission in endemic settings, addressing key uncertainties relating to the epidemiology of enteric fever identified through mathematical models, and enabling optimisation of vaccine strategies. METHODS/DESIGN: Using census-defined denominator populations of ≥100 000 individuals at sites in Malawi, Bangladesh and Nepal, the primary outcome is to characterise the burden of enteric fever in these populations over a 24-month period. During passive surveillance, clinical and household data, and laboratory samples will be collected from febrile individuals. In parallel, healthcare utilisation and water, sanitation and hygiene surveys will be performed to characterise healthcare-seeking behaviour and assess potential routes of transmission. The rates of both undiagnosed and subclinical exposure to typhoidalSalmonellae(seroincidence), identification of chronic carriage and population seroprevalence of typhoid infection will be assessed through age-stratified serosurveys performed at each site. Secondary attack rates will be estimated among household contacts of acute enteric fever cases and possible chronic carriers. ETHICS AND DISSEMINATION: This protocol has been ethically approved by the Oxford Tropical Research Ethics Committee, the icddr,b Institutional Review Board, the Malawian National Health Sciences Research Committee and College of Medicine Research Ethics Committee and Nepal Health Research Council. The study is being conducted in accordance with the principles of the Declaration of Helsinki and Good Clinical Practice. Informed consent was obtained before study enrolment. Results will be submitted to international peer-reviewed journals and presented at international conferences. TRIAL REGISTRATION NUMBER: ISRCTN 12131979. ETHICS REFERENCES: Oxford (Oxford Tropical Research Ethics Committee 39-15).Bangladesh (icddr,b Institutional Review Board PR-15119).Malawi (National Health Sciences Research Committee 15/5/1599).Nepal (Nepal Health Research Council 306/2015).

Thompson CN, Karkey A, Dongol S, Arjyal A, Wolbers M, Darton T, Farrar JJ, Thwaites GE, Dolecek C, Basnyat B, Baker S. 2017. Treatment Response in Enteric Fever in an Era of Increasing Antimicrobial Resistance: An Individual Patient Data Analysis of 2092 Participants Enrolled into 4 Randomized, Controlled Trials in Nepal. Clin Infect Dis, 64 (11), pp. 1522-1531. | Citations: 4 (Scopus) | Show Abstract | Read more

Background.: Enteric fever, caused by Salmonella Typhi and Salmonella Paratyphi A, is the leading cause of bacterial febrile disease in South Asia. Methods.: Individual data from 2092 patients with enteric fever randomized into 4 trials in Kathmandu, Nepal, were pooled. All trials compared gatifloxacin with 1 of the following comparator drugs: cefixime, chloramphenicol, ofloxacin, or ceftriaxone. Treatment outcomes were evaluated according to antimicrobial if S. Typhi/Paratyphi were isolated from blood. We additionally investigated the impact of changing bacterial antimicrobial susceptibility on outcome. Results.: Overall, 855 (41%) patients had either S. Typhi (n = 581, 28%) or S. Paratyphi A (n = 274, 13%) cultured from blood. There were 139 (6.6%) treatment failures with 1 death. Except for the last trial with ceftriaxone, the fluoroquinolone gatifloxacin was associated with equivalent or better fever clearance times and lower treatment failure rates in comparison to all other antimicrobials. However, we additionally found that the minimum inhibitory concentrations (MICs) against fluoroquinolones have risen significantly since 2005 and were associated with increasing fever clearance times. Notably, all organisms were susceptible to ceftriaxone throughout the study period (2005-2014), and the MICs against azithromycin declined, confirming the utility of these alternative drugs for enteric fever treatment. Conclusion.: The World Health Organization and local government health ministries in South Asia still recommend fluoroquinolones for enteric fever. This policy should change based on the evidence provided here. Rapid diagnostics are urgently required given the large numbers of suspected enteric fever patients with a negative culture.

Bhandari SS, Koirala P, Lohani S, Phuyal P, Basnyat B. 2017. Breathlessness at High Altitude: First Episode of Bronchoconstriction in an Otherwise Healthy Sojourner. High Alt Med Biol, 18 (2), pp. 179-181. | Show Abstract | Read more

Bhandari, Sanjeeb Sudarshan, Pranawa Koirala, Sadichhya Lohani, Pratibha Phuyal, and Buddha Basnyat. Breathlessness at high altitude: first episode of bronchoconstriction in an otherwise healthy sojourner. High Alt Med Biol.. 18:179-181, 2017-High-altitude illness is a collective term for less severe acute mountain sickness and more severe high-altitude pulmonary edema (HAPE) and high-altitude cerebral edema, which we can experience while traveling to high altitude. These get better when we get down to the lower altitudes. People with many comorbidities also have been traveling to high altitudes from the dawn of civilization. Obstructive airway diseases can be confused with HAPE at high altitude. Asthma is one of those obstructive pulmonary diseases, but it is shown to get better with travel to the altitudes higher than the residing altitude. We present a case of 55-year-old nonsmoker, athletic, female, a lowland resident who developed difficulty breathing for the first time at high altitude. She did not get better with the descent to lower altitude and timely intake of acetazolamide. Her pulmonary function test showed obstructive airway pattern, which got better with salbutamol/ipratropium nebulization and oxygen.

Kayastha GK, Ranjitkar N, Gurung R, Kc RK, Karki S, Shrestha R, Thapa RK, Rajbhandari P, Poudyal B, Acharya P et al. 2017. Treating Philadelphia chromosome/BCR-ABL1 positive patients with Glivec (Imatinib mesylate): 10 years' experience at Patan Hospital, Nepal. Br J Haematol, 177 (6), pp. 991-999. | Show Abstract | Read more

The Glivec International Patient Assistance Programme makes Glivec (Imatinib mesylate) available to Philadelphia chromosome/BCR-ABL1 positive patients with chronic myeloid leukaemia (CML) in Lower and Middle Income Countries (LMIC). We have established a large cohort of 211 CML patients who are eligible for Imatinib, in Kathmandu, Nepal. Thirty-one patients were lost to follow-up. We report on 180 CML patients with a median age of 38 years (range 9-81). Of these 180 patients, 162 underwent cytogenetic testing and 110 were investigated by reverse transcription polymerase chain reaction. One hundred and thirty-nine of the 180 patients (77·2%) had at least one optimal response. Taken together, our cohort has a 95% overall survival rate and 78% of the patients were still taking Glivec at a median time of 48·8 months (range 3-140 months). The number of patients who actually failed therapy, as defined by the LeukaemiaNet 2013 criteria, was 39 (21·7%). While our cohort has some differences with those in North America or Europe, we have shown Glivec is effective in inducing an optimal response in our patients in Nepal and that it is possible to deliver a clinical service for CML patients using tyrosine kinase inhibitors in resource-poor settings.

Kayastha GK, Ranjitkar N, Gurung R, Kc RK, Karki S, Shrestha R, Rajbhandari P, Thapa RK, Poudyal B, Acharya P et al. 2017. The use of Imatinib resistance mutation analysis to direct therapy in Philadelphia chromosome/BCR-ABL1 positive chronic myeloid leukaemia patients failing Imatinib treatment, in Patan Hospital, Nepal. Br J Haematol, 177 (6), pp. 1000-1007. | Citations: 1 (Web of Science Lite) | Show Abstract | Read more

Philadelphia chromosome/BCR-ABL1 positive chronic myeloid leukaemia (CML) can be successfully treated with Glivec (Imatinib), which is available free of cost through the Glivec International Patient Assistance programme (GIPAP) to patients with proven CML without means to pay for the drug. We review the acquired mutations in the tyrosine kinase encoded by the BCR-ABL1 gene underlying Glivec failure or resistance in a cohort of 388 imatinib-treated CML patients (149 Female and 239 male) registered between February 2003 and June 2016 in Nepal. Forty-five patients (11 female 34 male) were studied; 18 different BCR-ABL1 mutations were seen in 33 patients. P-loop mutation, Kinase domain and A-loop mutations were seen in 9, 16 and 4 patients respectively. Other mutations were seen in five patients. A T315I mutation was the most common mutation, followed by F359V and M244V. Sixteen mutations showed intermediate activity to complete resistance to Glivec. Among the 45 patients evaluated for BCR-ABL1 mutations, 4 were lost to follow-up, 14 died and 27 are still alive. Among the surviving patients, 16 are receiving Nilotinib, 5 Dasatinib and 3 Ponatinib, while 3 patients were referred to India, one of who received allogenic bone marrow transplantation. Understanding the spectrum of further acquired mutations in BCR-ABL1 may help to choose more specific targeted tyrosine kinase inhibitors that can be provided by GIPAP.

Phillips L, Basnyat B, Chang Y, Swenson ER, Harris NS. 2017. Findings of Cognitive Impairment at High Altitude: Relationships to Acetazolamide Use and Acute Mountain Sickness. High Alt Med Biol, 18 (2), pp. 121-127. | Citations: 1 (Scopus) | Show Abstract | Read more

Phillips, Lara, Buddha Basnyat, Yuchiao Chang, Erik R. Swenson, and N. Stuart Harris. Findings of cognitive impairment at high altitude: relationships to acetazolamide use and acute mountain sickness. High Alt Med Biol. 18:121-127, 2017. OBJECTIVE: Acute mountain sickness (AMS) is defined by patient-reported symptoms using the Lake Louise Score (LLS), which provides limited insight into any possible underlying central nervous system (CNS) dysfunction. Some evidence suggests AMS might coexist with altered neural functioning. Cognitive impairment (CI) may go undetected unless a sensitive test is applied. Our hypothesis was that a standardized test for mild CI would provide an objective measure of CNS dysfunction, which may correlate with the symptoms of AMS and so provide a potential new tool to better characterize altitude-related CNS dysfunction. We compared a cognitive screening tool with the LLS to see if it correlated with CNS dysfunction. METHODS: Adult native English-speaking subjects visiting Himalayan Rescue Association aid stations in Nepal at 3520 m (11,548 ft) and 4550 m (14,927 ft) were recruited. Subjects were administered the LLS and a slightly modified version of the environmental Quick mild cognitive impairment screen (eQmci). Medication use for altitude illness was recorded. Scores were compared using the Spearman's correlation coefficient. Data also included medication use. RESULTS: Seventy-nine subjects were enrolled. A cut-off of three or greater was used for the LLS to diagnose AMS and 67 or less for the eQmci to diagnose CI. There were 22 (28%) subjects who met criteria for AMS and 17 (22%) subjects who met criteria for CI. There was a weak correlation (r2 = 0.06, p = 0.04) between eQmci score and LLS. In matched subjects with identical LLS, recent acetazolamide use was associated with significantly more CI. CONCLUSION: Field assessment of CI using a rapid standardized tool demonstrated that a substantial number of subjects were found to have mild CI following rapid ascent to 3520-4550 m (11,548-14,927 ft). The weak correlation between the LLS and eQmci suggests that AMS does not result in CI. Use of acetazolamide appears to be associated with CI at all levels of AMS severity.

Kanaan NC, Peterson AL, Pun M, Holck PS, Starling J, Basyal B, Freeman TF, Gehner JR, Keyes L, Levin DR et al. 2017. Prophylactic Acetaminophen or Ibuprofen Results in Equivalent Acute Mountain Sickness Incidence at High Altitude: A Prospective Randomized Trial. Wilderness Environ Med, 28 (2), pp. 72-78. | Citations: 4 (Web of Science Lite) | Show Abstract | Read more

OBJECTIVE: Recent trials have demonstrated the usefulness of ibuprofen in the prevention of acute mountain sickness (AMS), yet the proposed anti-inflammatory mechanism remains unconfirmed. Acetaminophen and ibuprofen were tested for AMS prevention. We hypothesized that a greater clinical effect would be seen from ibuprofen due to its anti-inflammatory effects compared with acetaminophen's mechanism of possible symptom reduction by predominantly mediating nociception in the brain. METHODS: A double-blind, randomized trial was conducted testing acetaminophen vs ibuprofen for the prevention of AMS. A total of 332 non-Nepali participants were recruited at Pheriche (4371 m) and Dingboche (4410 m) on the Everest Base Camp trek. The participants were randomized to either acetaminophen 1000 mg or ibuprofen 600 mg 3 times a day until they reached Lobuche (4940 m), where they were reassessed. The primary outcome was AMS incidence measured by the Lake Louise Questionnaire score. RESULTS: Data from 225 participants who met inclusion criteria were analyzed. Twenty-five participants (22.1%) in the acetaminophen group and 18 (16.1%) in the ibuprofen group developed AMS (P = .235). The combined AMS incidence was 19.1% (43 participants), 14 percentage points lower than the expected AMS incidence of untreated trekkers in prior studies at this location, suggesting that both interventions reduced the incidence of AMS. CONCLUSIONS: We found little evidence of any difference between acetaminophen and ibuprofen groups in AMS incidence. This suggests that AMS prevention may be multifactorial, affected by anti-inflammatory inhibition of the arachidonic-acid pathway as well as other analgesic mechanisms that mediate nociception. Additional study is needed.

Saad NJ, Bowles CC, Grenfell BT, Basnyat B, Arjyal A, Dongol S, Karkey A, Baker S, Pitzer VE. 2017. The impact of migration and antimicrobial resistance on the transmission dynamics of typhoid fever in Kathmandu, Nepal: A mathematical modelling study. PLoS Negl Trop Dis, 11 (5), pp. e0005547. | Show Abstract | Read more

BACKGROUND: A substantial proportion of the global burden of typhoid fever occurs in South Asia. Kathmandu, Nepal experienced a substantial increase in the number of typhoid fever cases (caused by Salmonella Typhi) between 2000 and 2003, which subsequently declined but to a higher endemic level than in 2000. This epidemic of S. Typhi coincided with an increase in organisms with reduced susceptibility against fluoroquinolones, the emergence of S. Typhi H58, and an increase in the migratory population in Kathmandu. METHODS: We devised a mathematical model to investigate the potential epidemic drivers of typhoid in Kathmandu and fit this model to weekly data of S. Typhi cases between April 1997 and June 2011 and the age distribution of S. Typhi cases. We used this model to determine if the typhoid epidemic in Kathmandu was driven by heightened migration, the emergence of organisms with reduced susceptibility against fluoroquinolones or a combination of these factors. RESULTS: Models allowing for the migration of susceptible individuals into Kathmandu alone or in combination with the emergence of S. Typhi with reduced susceptibility against fluoroquinolones provided a good fit for the data. The emergence of organisms with reduced susceptibility against fluoroquinolones organisms alone, either through an increase in disease duration or increased transmission, did not fully explain the pattern of S. Typhi infections. CONCLUSIONS: Our analysis is consistent with the hypothesis that the increase in typhoid fever in Kathmandu was associated with the migration of susceptible individuals into the city and aided by the emergence of reduced susceptibility against fluoroquinolones. These data support identifying and targeting migrant populations with typhoid immunization programmes to prevent transmission and disease.

Jeong C, Peter BM, Basnyat B, Neupane M, Beall CM, Childs G, Craig SR, Novembre J, Di Rienzo A. 2017. A longitudinal cline characterizes the genetic structure of human populations in the Tibetan plateau. PLoS One, 12 (4), pp. e0175885. | Citations: 2 (Scopus) | Show Abstract | Read more

Indigenous populations of the Tibetan plateau have attracted much attention for their good performance at extreme high altitude. Most genetic studies of Tibetan adaptations have used genetic variation data at the genome scale, while genetic inferences about their demography and population structure are largely based on uniparental markers. To provide genome-wide information on population structure, we analyzed new and published data of 338 individuals from indigenous populations across the plateau in conjunction with worldwide genetic variation data. We found a clear signal of genetic stratification across the east-west axis within Tibetan samples. Samples from more eastern locations tend to have higher genetic affinity with lowland East Asians, which can be explained by more gene flow from lowland East Asia onto the plateau. Our findings corroborate a previous report of admixture signals in Tibetans, which were based on a subset of the samples analyzed here, but add evidence for isolation by distance in a broader geospatial context.

Cho JI, Basnyat B, Jeong C, Di Rienzo A, Childs G, Craig SR, Sun J, Beall CM. 2017. Ethnically Tibetan women in Nepal with low hemoglobin concentration have better reproductive outcomes. Evol Med Public Health, 2017 (1), pp. 82-96. | Show Abstract | Read more

Background and objectives: Tibetans have distinctively low hemoglobin concentrations at high altitudes compared with visitors and Andean highlanders. This study hypothesized that natural selection favors an unelevated hemoglobin concentration among Tibetans. It considered nonheritable sociocultural factors affecting reproductive success and tested the hypotheses that a higher percent of oxygen saturation of hemoglobin (indicating less stress) or lower hemoglobin concentration (indicating dampened response) associated with higher lifetime reproductive success. Methodology: We sampled 1006 post-reproductive ethnically Tibetan women residing at 3000-4100 m in Nepal. We collected reproductive histories by interviews in native dialects and noninvasive physiological measurements. Regression analyses selected influential covariates of measures of reproductive success: the numbers of pregnancies, live births and children surviving to age 15. Results: Taking factors such as marriage status, age of first birth and access to health care into account, we found a higher percent of oxygen saturation associated weakly and an unelevated hemoglobin concentration associated strongly with better reproductive success. Women who lost all their pregnancies or all their live births had hemoglobin concentrations significantly higher than the sample mean. Elevated hemoglobin concentration associated with a lower probability a pregnancy progressed to a live birth. Conclusions and implications: These findings are consistent with the hypothesis that unelevated hemoglobin concentration is an adaptation shaped by natural selection resulting in the relatively low hemoglobin concentration of Tibetans compared with visitors and Andean highlanders.

Laxminarayan R, Kakkar M, Horby P, Malavige GN, Basnyat B. 2017. Emerging and re-emerging infectious disease threats in South Asia: status, vulnerability, preparedness, and outlook. BMJ, 357 pp. j1447. | Read more

Griva K, Stygall J, Wilson MH, Martin D, Levett D, Mitchell K, Mythen M, Montgomery HE, Grocott MP, Aref-Adib G et al. 2017. Caudwell Xtreme Everest: A prospective study of the effects of environmental hypoxia on cognitive functioning. PLoS One, 12 (3), pp. e0174277. | Citations: 1 (Scopus) | Show Abstract | Read more

BACKGROUND: The neuropsychological consequences of exposure to environmental hypobaric hypoxia (EHH) remain unclear. We thus investigated them in a large group of healthy volunteers who trekked to Mount Everest base camp (5,300 m). METHODS: A neuropsychological (NP) test battery assessing memory, language, attention, and executive function was administered to 198 participants (age 44.5±13.7 years; 60% male). These were studied at baseline (sea level), 3,500 m (Namche Bazaar), 5,300 m (Everest Base Camp) and on return to 1,300 m (Kathmandu) (attrition rate 23.7%). A comparable control group (n = 25; age 44.5±14.1 years; 60% male) for comparison with trekkers was tested at/or near sea level over an equivalent timeframe so as to account for learning effects associated with repeat testing. The Reliable Change Index (RCI) was used to calculate changes in cognition and neuropsychological function during and after exposure to EHH relative to controls. RESULTS: Overall, attention, verbal ability and executive function declined in those exposed to EHH when the performance of the control group was taken into account (RCI .05 to -.95) with decline persisting at descent. Memory and psychomotor function showed decline at highest ascent only (RCI -.08 to -.56). However, there was inter-individual variability in response: whilst NP performance declined in most, this improved in some trekkers. Cognitive decline was greater amongst older people (r = .42; p < .0001), but was otherwise not consistently associated with socio-demographic, mood, or physiological variables. CONCLUSIONS: After correcting for learning effects, attention, verbal abilities and executive functioning declined with exposure to EHH. There was considerable individual variability in the response of brain function to sustained hypoxia with some participants not showing any effects of hypoxia. This might have implications for those facing sustained hypoxia as a result of any disease.

Zafren K, Pun M, Regmi N, Bashyal G, Acharya B, Gautam S, Jamarkattel S, Lamichhane SR, Acharya S, Basnyat B. 2017. High altitude illness in pilgrims after rapid ascent to 4380 M. Travel Med Infect Dis, 16 pp. 31-34. | Show Abstract | Read more

BACKGROUND: The goal of the study was to characterize high altitude illness in Nepali pilgrims. METHODS: We kept standardized records at the Himalayan Rescue Association (HRA) Temporary Health Camp at Gosainkund Lake (4380 m) in the Nepal Himalaya during the annual Janai Purnima Festival in 2014. Records included rate of ascent and Lake Louise Score (LLS). We defined High Altitude Headache (HAH) as headache alone or LLS = 2. Acute Mountain Sickness (AMS) was LLS≥3. High Altitude Cerebral Edema (HACE) was AMS with ataxia or altered mental status. RESULTS: An estimated 10,000 pilgrims ascended rapidly, most in 1-2 days, from Dhunche (1960 m) to Gosainkund Lake (4380 m). We saw 769 patients, of whom 86 had HAH. There were 226 patients with AMS, including 11 patients with HACE. We treated patients with HACE using dexamethasone and supplemental oxygen prior to rapid descent. Each patient with HACE descended carried by a porter. There were no fatalities due to HACE. There were no cases of High Altitude Pulmonary Edema (HAPE). CONCLUSIONS: HAH and AMS were common in pilgrims ascending rapidly to 4380 m. There were 11 cases of HACE, treated with dexamethasone, supplemental oxygen and descent. There were no fatalities.

Dobinson HC, Gibani MM, Jones C, Thomaides-Brears HB, Voysey M, Darton TC, Waddington CS, Campbell D, Milligan I, Zhou L et al. 2017. Evaluation of the Clinical and Microbiological Response to Salmonella Paratyphi A Infection in the First Paratyphoid Human Challenge Model. Clin Infect Dis, 64 (8), pp. 1066-1073. | Citations: 6 (Web of Science Lite) | Show Abstract | Read more

Background: To expedite the evaluation of vaccines against paratyphoid fever, we aimed to develop the first human challenge model of Salmonella enterica serovar Paratyphi A infection. Methods: Two groups of 20 participants underwent oral challenge with S. Paratyphi A following sodium bicarbonate pretreatment at 1 of 2 dose levels (group 1: 1-5 × 103 colony-forming units [CFU] and group 2: 0.5-1 × 103 CFU). Participants were monitored in an outpatient setting with daily clinical review and collection of blood and stool cultures. Antibiotic treatment was started when prespecified diagnostic criteria were met (temperature ≥38°C for ≥12 hours and/or bacteremia) or at day 14 postchallenge. Results: The primary study objective was achieved following challenge with 1-5 × 103 CFU (group 1), which resulted in an attack rate of 12 of 20 (60%). Compared with typhoid challenge, paratyphoid was notable for high rates of subclinical bacteremia (at this dose, 11/20 [55%]). Despite limited symptoms, bacteremia persisted for up to 96 hours after antibiotic treatment (median duration of bacteremia, 53 hours [interquartile range, 24-85 hours]). Shedding of S. Paratyphi A in stool typically preceded onset of bacteremia. Conclusions: Challenge with S. Paratyphi A at a dose of 1-5 × 103 CFU was well tolerated and associated with an acceptable safety profile. The frequency and persistence of bacteremia in the absence of clinical symptoms was notable, and markedly different from that seen in previous typhoid challenge studies. We conclude that the paratyphoid challenge model is suitable for the assessment of vaccine efficacy using endpoints that include bacteremia and/or symptomatology. Clinical Trials Registration: NCT02100397.

Kanaan NC, Peterson AL, Pun M, Thapa GB, Tiwari A, Basyal B, Holck PS, Starling J, Freeman TF, Gehner JR et al. 2017. In Reply to Drs Lipman and Hackett. Wilderness Environ Med, 28 (4), pp. 385-387. | Read more

Karki M, Pandit S, Baker S, Basnyat B. 2016. Cotrimoxazole treats fluoroquinolone-resistant Salmonella typhi H58 infection. BMJ Case Rep, 2016 pp. bcr2016217223-bcr2016217223. | Citations: 3 (Scopus) | Show Abstract | Read more

A woman aged 20 years presented with fever and no localising signs. She was treated with cotrimoxazole and the subsequent blood culture was positive for Salmonella typhi (S. typhi), which was resistant to fluoroquinolones but susceptible to cotrimoxazole. Genotyping identified an FQ-R subclade of H58 S. typhi Fever clearance time was 4 days after starting the antibiotics, and no relapses were noted on 2 months of follow-up. This inexpensive, well-known and easily available antimicrobial could be suitably redeployed for fluoroquinolone-resistant enteric fever in South Asia.

Basnyat B. 2016. Typhoid versus typhus fever in post-earthquake Nepal. Lancet Glob Health, 4 (8), pp. e516-e517. | Citations: 6 (Scopus) | Read more

Wong VK, Baker S, Connor TR, Pickard D, Page AJ, Dave J, Murphy N, Holliman R, Sefton A, Millar M et al. 2016. An extended genotyping framework for Salmonella enterica serovar Typhi, the cause of human typhoid. Nat Commun, 7 pp. 12827. | Citations: 11 (Web of Science Lite) | Show Abstract | Read more

The population of Salmonella enterica serovar Typhi (S. Typhi), the causative agent of typhoid fever, exhibits limited DNA sequence variation, which complicates efforts to rationally discriminate individual isolates. Here we utilize data from whole-genome sequences (WGS) of nearly 2,000 isolates sourced from over 60 countries to generate a robust genotyping scheme that is phylogenetically informative and compatible with a range of assays. These data show that, with the exception of the rapidly disseminating H58 subclade (now designated genotype 4.3.1), the global S. Typhi population is highly structured and includes dozens of subclades that display geographical restriction. The genotyping approach presented here can be used to interrogate local S. Typhi populations and help identify recent introductions of S. Typhi into new or previously endemic locations, providing information on their likely geographical source. This approach can be used to classify clinical isolates and provides a universal framework for further experimental investigations.

Basnyat B. 2016. Aftershocks of scrub typhus in Nepal - Author's reply. Lancet Glob Health, 4 (10), pp. e688. | Read more

International Typhoid Consortium, Wong VK, Holt KE, Okoro C, Baker S, Pickard DJ, Marks F, Page AJ, Olanipekun G, Munir H et al. 2016. Molecular Surveillance Identifies Multiple Transmissions of Typhoid in West Africa. PLoS Negl Trop Dis, 10 (9), pp. e0004781. | Citations: 1 (Web of Science Lite) | Show Abstract | Read more

BACKGROUND: The burden of typhoid in sub-Saharan African (SSA) countries has been difficult to estimate, in part, due to suboptimal laboratory diagnostics. However, surveillance blood cultures at two sites in Nigeria have identified typhoid associated with Salmonella enterica serovar Typhi (S. Typhi) as an important cause of bacteremia in children. METHODS: A total of 128 S. Typhi isolates from these studies in Nigeria were whole-genome sequenced, and the resulting data was used to place these Nigerian isolates into a worldwide context based on their phylogeny and carriage of molecular determinants of antibiotic resistance. RESULTS: Several distinct S. Typhi genotypes were identified in Nigeria that were related to other clusters of S. Typhi isolates from north, west and central regions of Africa. The rapidly expanding S. Typhi clade 4.3.1 (H58) previously associated with multiple antimicrobial resistances in Asia and in east, central and southern Africa, was not detected in this study. However, antimicrobial resistance was common amongst the Nigerian isolates and was associated with several plasmids, including the IncHI1 plasmid commonly associated with S. Typhi. CONCLUSIONS: These data indicate that typhoid in Nigeria was established through multiple independent introductions into the country, with evidence of regional spread. MDR typhoid appears to be evolving independently of the haplotype H58 found in other typhoid endemic countries. This study highlights an urgent need for routine surveillance to monitor the epidemiology of typhoid and evolution of antimicrobial resistance within the bacterial population as a means to facilitate public health interventions to reduce the substantial morbidity and mortality of typhoid.

Donegani E, Paal P, Küpper T, Hefti U, Basnyat B, Carceller A, Bouzat P, van der Spek R, Hillebrandt D. 2016. Drug Use and Misuse in the Mountains: A UIAA MedCom Consensus Guide for Medical Professionals. High Alt Med Biol, 17 (3), pp. 157-184. | Citations: 3 (Web of Science Lite) | Show Abstract | Read more

Donegani, Enrico, Peter Paal, Thomas Küpper, Urs Hefti, Buddha Basnyat, Anna Carceller, Pierre Bouzat, Rianne van der Spek, and David Hillebrandt. Drug use and misuse in the mountains: a UIAA MedCom consensus guide for medical professionals. High Alt Med Biol. 17:157-184, 2016.-Aims: The aim of this review is to inform mountaineers about drugs commonly used in mountains. For many years, drugs have been used to enhance performance in mountaineering. It is the UIAA (International Climbing and Mountaineering Federation-Union International des Associations d'Alpinisme) Medcom's duty to protect mountaineers from possible harm caused by uninformed drug use. The UIAA Medcom assessed relevant articles in scientific literature and peer-reviewed studies, trials, observational studies, and case series to provide information for physicians on drugs commonly used in the mountain environment. Recommendations were graded according to criteria set by the American College of Chest Physicians. RESULTS: Prophylactic, therapeutic, and recreational uses of drugs relevant to mountaineering are presented with an assessment of their risks and benefits. CONCLUSIONS: If using drugs not regulated by the World Anti-Doping Agency (WADA), individuals have to determine their own personal standards for enjoyment, challenge, acceptable risk, and ethics. No system of drug testing could ever, or should ever, be policed for recreational climbers. Sponsored climbers or those who climb for status need to carefully consider both the medical and ethical implications if using drugs to aid performance. In some countries (e.g., Switzerland and Germany), administrative systems for mountaineering or medication control dictate a specific stance, but for most recreational mountaineers, any rules would be unenforceable and have to be a personal decision, but should take into account the current best evidence for risk, benefit, and sporting ethics.

Keyes LE, Mather L, Duke C, Regmi N, Phelan B, Pant S, Starling J, McElwee M, Cole D, McConnell T et al. 2016. Older age, chronic medical conditions and polypharmacy in Himalayan trekkers in Nepal: an epidemiologic survey and case series. J Travel Med, 23 (6), pp. taw052-taw052. | Citations: 1 (Web of Science Lite) | Show Abstract | Read more

BACKGROUND: The number of tourists in Nepal doubled between 2003 and 2013 is nearly 800 000. With the increased popularity of trekking, the number of those with pre-existing medical conditions requiring access to healthcare is likely to increase. We therefore sought to characterize the demographics and health status of trekkers on the Everest Base Camp route in the Solukhumbu Valley. In addition, we report cases that illustrate the potential complications of an ageing and medicated population of trekkers with underlying diseases. METHODS: Trekkers over 18 years were enrolled in a larger observational cohort study on blood pressure at high altitude at 2860 m. They answered a questionnaire regarding demographics, medical history and current medications. Acute medical problems relating to medication use that were brought to the attention of investigators were documented and are presented as case reports. RESULTS: We enrolled 670 trekkers, 394 (59%) male, with a mean age of 48 years (range 18-76). Pre-existing medical conditions were reported by 223 participants (33%). The most frequent conditions included hypertension, hypercholesterolemia, migraines and thyroid dysfunction. A total of 276 participants (41%) reported taking one or more medications. The most common medications were acetazolamide (79, 12%), antihypertensives (50, 8%) and NSAIDs (47, 7%), with 30 classes of drugs represented. Excluding acetazolamide, older trekkers (age >50 years) were more likely than younger ones to take medications (OR = 2.17; 95% CI 1.57-3.00; P <0.05). Acetazolamide use was not related to age. CONCLUSIONS: Our findings illustrate a wide variety of medical conditions present in trekkers in Nepal with wide-ranging potential complications that could pose difficulties in areas where medical care is scarce and evacuation difficult. Our cases illustrate the potential problems polypharmacy poses in trekkers, and the need for local and expedition healthcare workers to be aware of, and prepared for the common medical conditions present.

Khor CC, Do T, Jia H, Nakano M, George R, Abu-Amero K, Duvesh R, Chen LJ, Li Z, Nongpiur ME et al. 2016. Genome-wide association study identifies five new susceptibility loci for primary angle closure glaucoma. Nat Genet, 48 (5), pp. 556-562. | Citations: 23 (Web of Science Lite) | Show Abstract | Read more

Primary angle closure glaucoma (PACG) is a major cause of blindness worldwide. We conducted a genome-wide association study (GWAS) followed by replication in a combined total of 10,503 PACG cases and 29,567 controls drawn from 24 countries across Asia, Australia, Europe, North America, and South America. We observed significant evidence of disease association at five new genetic loci upon meta-analysis of all patient collections. These loci are at EPDR1 rs3816415 (odds ratio (OR) = 1.24, P = 5.94 × 10(-15)), CHAT rs1258267 (OR = 1.22, P = 2.85 × 10(-16)), GLIS3 rs736893 (OR = 1.18, P = 1.43 × 10(-14)), FERMT2 rs7494379 (OR = 1.14, P = 3.43 × 10(-11)), and DPM2-FAM102A rs3739821 (OR = 1.15, P = 8.32 × 10(-12)). We also confirmed significant association at three previously described loci (P < 5 × 10(-8) for each sentinel SNP at PLEKHA7, COL11A1, and PCMTD1-ST18), providing new insights into the biology of PACG.

Arjyal A, Basnyat B, Nhan HT, Koirala S, Giri A, Joshi N, Shakya M, Pathak KR, Mahat SP, Prajapati SP et al. 2016. Gatifloxacin versus ceftriaxone for uncomplicated enteric fever in Nepal: an open-label, two-centre, randomised controlled trial. Lancet Infect Dis, 16 (5), pp. 535-545. | Citations: 11 (Web of Science Lite) | Show Abstract | Read more

BACKGROUND: Because treatment with third-generation cephalosporins is associated with slow clinical improvement and high relapse burden for enteric fever, whereas the fluoroquinolone gatifloxacin is associated with rapid fever clearance and low relapse burden, we postulated that gatifloxacin would be superior to the cephalosporin ceftriaxone in treating enteric fever. METHODS: We did an open-label, randomised, controlled, superiority trial at two hospitals in the Kathmandu valley, Nepal. Eligible participants were children (aged 2-13 years) and adult (aged 14-45 years) with criteria for suspected enteric fever (body temperature ≥38·0°C for ≥4 days without a focus of infection). We randomly assigned eligible patients (1:1) without stratification to 7 days of either oral gatifloxacin (10 mg/kg per day) or intravenous ceftriaxone (60 mg/kg up to 2 g per day for patients aged 2-13 years, or 2 g per day for patients aged ≥14 years). The randomisation list was computer-generated using blocks of four and six. The primary outcome was a composite of treatment failure, defined as the occurrence of at least one of the following: fever clearance time of more than 7 days after treatment initiation; the need for rescue treatment on day 8; microbiological failure (ie, blood cultures positive for Salmonella enterica serotype Typhi, or Paratyphi A, B, or C) on day 8; or relapse or disease-related complications within 28 days of treatment initiation. We did the analyses in the modified intention-to-treat population, and subpopulations with either confirmed blood-culture positivity, or blood-culture negativity. The trial was powered to detect an increase of 20% in the risk of failure. This trial was registered at ClinicalTrials.gov, number NCT01421693, and is now closed. FINDINGS: Between Sept 18, 2011, and July 14, 2014, we screened 725 patients for eligibility. On July 14, 2014, the trial was stopped early by the data safety and monitoring board because S Typhi strains with high-level resistance to ciprofloxacin and gatifloxacin had emerged. At this point, 239 were in the modified intention-to-treat population (120 assigned to gatifloxacin, 119 to ceftriaxone). 18 (15%) patients who received gatifloxacin had treatment failure, compared with 19 (16%) who received ceftriaxone (hazard ratio [HR] 1·04 [95% CI 0·55-1·98]; p=0·91). In the culture-confirmed population, 16 (26%) of 62 patients who received gatifloxacin failed treatment, compared with four (7%) of 54 who received ceftriaxone (HR 0·24 [95% CI 0·08-0·73]; p=0·01). Treatment failure was associated with the emergence of S Typhi exhibiting resistance against fluoroquinolones, requiring the trial to be stopped. By contrast, in patients with a negative blood culture, only two (3%) of 58 who received gatifloxacin failed treatment versus 15 (23%) of 65 who received ceftriaxone (HR 7·50 [95% CI 1·71-32·80]; p=0·01). A similar number of non-serious adverse events occurred in each treatment group, and no serious events were reported. INTERPRETATION: Our results suggest that fluoroquinolones should no longer be used for treatment of enteric fever in Nepal. Additionally, under our study conditions, ceftriaxone was suboptimum in a high proportion of patients with culture-negative enteric fever. Since antimicrobials, specifically fluoroquinolones, are one of the only routinely used control measures for enteric fever, the assessment of novel diagnostics, new treatment options, and use of existing vaccines and development of next-generation vaccines are now a high priority. FUNDING: Wellcome Trust and Li Ka Shing Foundation.

Karkey A, Jombart T, Walker AW, Thompson CN, Torres A, Dongol S, Tran Vu Thieu N, Pham Thanh D, Tran Thi Ngoc D, Voong Vinh P et al. 2016. The Ecological Dynamics of Fecal Contamination and Salmonella Typhi and Salmonella Paratyphi A in Municipal Kathmandu Drinking Water. PLoS Negl Trop Dis, 10 (1), pp. e0004346. | Citations: 9 (Web of Science Lite) | Show Abstract | Read more

One of the UN sustainable development goals is to achieve universal access to safe and affordable drinking water by 2030. It is locations like Kathmandu, Nepal, a densely populated city in South Asia with endemic typhoid fever, where this goal is most pertinent. Aiming to understand the public health implications of water quality in Kathmandu we subjected weekly water samples from 10 sources for one year to a range of chemical and bacteriological analyses. We additionally aimed to detect the etiological agents of typhoid fever and longitudinally assess microbial diversity by 16S rRNA gene surveying. We found that the majority of water sources exhibited chemical and bacterial contamination exceeding WHO guidelines. Further analysis of the chemical and bacterial data indicated site-specific pollution, symptomatic of highly localized fecal contamination. Rainfall was found to be a key driver of this fecal contamination, correlating with nitrates and evidence of S. Typhi and S. Paratyphi A, for which DNA was detectable in 333 (77%) and 303 (70%) of 432 water samples, respectively. 16S rRNA gene surveying outlined a spectrum of fecal bacteria in the contaminated water, forming complex communities again displaying location-specific temporal signatures. Our data signify that the municipal water in Kathmandu is a predominant vehicle for the transmission of S. Typhi and S. Paratyphi A. This study represents the first extensive spatiotemporal investigation of water pollution in an endemic typhoid fever setting and implicates highly localized human waste as the major contributor to poor water quality in the Kathmandu Valley.

Paudyal B, Paudel K, Shakya M, Basnyat B. 2016. Paradoxical reaction to antitubercular treatment in a case of pulmonary tuberculosis. BMJ Case Rep, 2016 pp. bcr2015214285-bcr2015214285. | Show Abstract | Read more

A 51-year-old man presented with intermittent fever, mild cough and loss of appetite of 1-month duration. His sputum smear was positive for acid-fast bacilli and his chest radiograph revealed apical infiltrations. The patient was treated with antitubercular therapy (ATT), recovered and was well for 1 month, after which he suddenly developed focal seizures. MRI of the brain with gadolinium enhancement showed high intensity nodular foci in the frontal, parietal and occipital regions. The patient was diagnosed as a case of paradoxical reaction to ATT, and was successfully managed with continued ATT and adjunctive steroid therapy.

Pham Thanh D, Karkey A, Dongol S, Ho Thi N, Thompson CN, Rabaa MA, Arjyal A, Holt KE, Wong V, Tran Vu Thieu N et al. 2016. A novel ciprofloxacin-resistant subclade of H58 Salmonella Typhi is associated with fluoroquinolone treatment failure. Elife, 5 (MARCH2016), pp. e14003. | Citations: 17 (Web of Science Lite) | Show Abstract | Read more

The interplay between bacterial antimicrobial susceptibility, phylogenetics and patient outcome is poorly understood. During a typhoid clinical treatment trial in Nepal, we observed several treatment failures and isolated highly fluoroquinolone-resistant Salmonella Typhi (S. Typhi). Seventy-eight S. Typhi isolates were genome sequenced and clinical observations, treatment failures and fever clearance times (FCTs) were stratified by lineage. Most fluoroquinolone-resistant S. Typhi belonged to a specific H58 subclade. Treatment failure with S. Typhi-H58 was significantly less frequent with ceftriaxone (3/31; 9.7%) than gatifloxacin (15/34; 44.1%)(Hazard Ratio 0.19, p=0.002). Further, for gatifloxacin-treated patients, those infected with fluoroquinolone-resistant organisms had significantly higher median FCTs (8.2 days) than those infected with susceptible (2.96) or intermediately resistant organisms (4.01)(pS. Typhi clade internationally, but there are no data regarding disease outcome with this organism. We report an emergent new subclade of S. Typhi-H58 that is associated with fluoroquinolone treatment failure.

Paudyal B, Shakya M, Basnyat B. 2016. Spontaneous hypoglycaemia in a patient with Graves' disease. BMJ Case Rep, 2016 pp. bcr2016214801-bcr2016214801. | Show Abstract | Read more

A 23-year-old man, on treatment for Graves' disease, presented to the emergency department, with 2 separate episodes of loss of consciousness. During the first episode, the initial serum glucose was 19 mg/mL, and 44 mg/dL during the second episode. The patient was non-diabetic, and had elevated blood insulin, C peptide and insulin antibody levels. His abdominal radiographic findings were normal. He was diagnosed with Hirata disease, and put on propylthiouracil as a replacement for carbimazole. Hypoglycaemia was managed with dextrose infusions and frequent meals. The patient's condition improved and he had no further episodes of hypoglycaemia during the follow-up period.

Basnyat B. 2016. Post-earthquake Nepal: Acute-on-chronic problems. Natl Med J India, 29 (1), pp. 27. | Read more

Basnyat B. 2016. Letter from Nepal: Post-earthquake Nepal: Acute-on-chronic problems National Medical Journal of India, 29 (1), pp. 27.

Izopet J, Labrique AB, Basnyat B, Dalton HR, Kmush B, Heaney CD, Nelson KE, Ahmed ZB, Zaman K, Mansuy J-M et al. 2015. Hepatitis E virus seroprevalence in three hyperendemic areas: Nepal, Bangladesh and southwest France. J Clin Virol, 70 pp. 39-42. | Citations: 20 (Scopus) | Show Abstract | Read more

BACKGROUND: Hepatitis E causes a significant burden of disease in developing countries and has recently been increasingly recognized in developed countries. Comparing population anti-hepatitis E virus (HEV) seroprevalence across populations has been difficult. OBJECTIVES: The aim of this study was to compare the anti-HEV IgG seroprevalence in both adults and children in three hyper-endemic areas (Nepal, Bangladesh and southwest France) using a sensitive, commercial anti-HEV IgG assay. STUDY DESIGN: Serum or plasma from adults and children in Nepal (n=498), Bangladesh (n=1,009) and Southwest France (n=1031) were tested for anti-HEV IgG using the Wantai assay. RESULTS: After age-standardization, anti-HEV IgG seroprevalence was 47.1%, 49.8% and 34.0% in Nepal, Bangladesh and southwest France, respectively. There was no difference in seroprevalence by gender in any of the countries. A paucity of infections in children 1-10 years-old was consistently observed (less than 15%) at all 3 locations. CONCLUSIONS: Surprisingly similar high rates of anti-HEV antibodies were detected using a common, sensitive assay. Despite differences in the epidemiology and circulating genotype of HEV in Nepal, Bangladesh and southwest France, this study found more similarities in population seroprevalence than expected.

Basnyat B. 2015. Tackle Nepal's typhoid problem now. Nature, 524 (7565), pp. 267. | Citations: 3 (Web of Science Lite) | Read more

Kingston HWF, Blacksell SD, Tanganuchitcharnchai A, Laongnualpanich A, Basnyat B, Day NPJ, Paris DH. 2015. Comparative Accuracy of the InBios Scrub Typhus Detect IgM Rapid Test for the Detection of IgM Antibodies by Using Conventional Serology. Clin Vaccine Immunol, 22 (10), pp. 1130-1132. | Citations: 12 (Scopus) | Show Abstract | Read more

This study investigated the comparative accuracy of a recombinant 56-kDa type-specific antigen-based rapid diagnostic test (RDT) for scrub typhus for the detection of IgM antibodies by using conventional serology in well-characterized serum samples from undifferentiated febrile illness patients. The RDT showed high specificity and promising comparative accuracy, with 82% sensitivity and 98% specificity for samples defined positive at an IgM indirect immunofluorescence assay positivity cutoff titer of ≥1:1,600 versus 92% and 95% at ≥1:6,400, respectively.

Basnyat B, Starling JM. 2015. Infectious Diseases at High Altitude. Microbiol Spectr, 3 (4), | Citations: 2 (Scopus) | Show Abstract | Read more

Travel to elevations above 2,500 m is an increasingly common activity undertaken by a diverse population of individuals. These may be trekkers, climbers, miners in high-altitude sites in South America, and more recently, soldiers deployed for high-altitude duty in remote areas of the world. What is also being increasingly recognized is the plight of the millions of pilgrims, many with comorbidities, who annually ascend to high-altitude sacred areas. There are also 400 million people who reside permanently in high mountain ranges, which cover one-fifth of the Earth's surface. Many of these high-altitude areas are in developing countries, for example, the Himalayan range in South Asia. Although high-altitude areas may not harbor any specific infectious disease agents, it is important to know about the pathogens encountered in the mountains to be better able to help both the ill sojourner and the native high-altitude dweller. Often the same pathogens prevalent in the surrounding lowlands are found at high altitude, but various factors such as immunomodulation, hypoxia, poor physiological adaptation, and harsh environmental stressors at high altitude may enhance susceptibility to these pathogens. Against this background, various gastrointestinal, respiratory, dermatological, neurological, and other infections encountered at high altitude are discussed.

Parry CM, Thieu NTV, Dolecek C, Karkey A, Gupta R, Turner P, Dance D, Maude RR, Ha V, Tran CN et al. 2015. Erratum for Parry et al., Clinically and microbiologically derived azithromycin susceptibility breakpoints for Salmonella enterica serovars Typhi and Paratyphi A. Antimicrob Agents Chemother, 59 (7), pp. 4364. | Citations: 2 (Scopus) | Read more

Parry CM, Thieu NTV, Dolecek C, Karkey A, Gupta R, Turner P, Dance D, Maude RR, Ha V, Tran CN et al. 2015. Clinically and Microbiologically Derived Azithromycin Susceptibility Breakpoints for Salmonella enterica Serovars Typhi and Paratyphi A (vol 59, pg 2756, 2015) ANTIMICROBIAL AGENTS AND CHEMOTHERAPY, 59 (7), pp. 4364-4364. | Citations: 2 (Web of Science Lite) | Read more

Basnyat B, Dalton HR, Kamar N, Rein DB, Labrique A, Farrar J, Piot P, 21 signatories. 2015. Nepali earthquakes and the risk of an epidemic of hepatitis E. Lancet, 385 (9987), pp. 2572-2573. | Citations: 10 (Web of Science Lite) | Read more

Basnyat B, Pokharel P, Dixit S, Giri S. 2015. Antibiotic Use, Its Resistance in Nepal and Recommendations for Action: A Situation Analysis. J Nepal Health Res Counc, 13 (30), pp. 102-111. | Citations: 1 (Scopus) | Show Abstract

Antibiotics are crucial, life-saving medicines in the fight against infectious disease, but resistance to these drugs is growing all over. This article presents key findings from a detailed situation analysis produced by the Global Antibiotic Resistance Partnership (GARP)-Nepal working group. In the absence of nationally-representative surveillance, it is not possible to fully describe antibiotic resistance in the country, but many important bacterial pathogens are highly resistant to most first-line and some second-line antibiotics, according to available reports. In credible studies, more than half of Escherichia coli, Klebsiella pneumoniae and Streptococcus pneumoniae isolates tested, and over 30 percent of some Shigella spp. and Vibrio cholerae isolates were resistant to first-line antibiotics. The findings for Neisseria gonorrheae and hospital-acquired Staphylococcus aureus are similar. Antibiotic use in animal food is poorly documented in Nepal, but it is commonly acknowledged to be widespread, contributing to the overall antibiotic resistance burden. The volume of veterinary antibiotic sales in Nepal rose over 50 percent from 2008 to 2012, most through retailers without veterinarian prescription. Antibiotics are necessary to treat infections in animals, but they are also used extensively for preventing disease, a use that can be restricted without jeopardizing animal or human health. They may also be used for promoting animal growth, which can be eliminated with no health consequences. Nepal has made important advances in reducing mortality and morbidity and increasing health coverage, but has not yet taken steps to address antibiotic resistance. The GARP-Nepal working group outlines the components of a national strategy on antibiotic resistance, consistent with the recent call by the World Health Organization for national action plans, to be developed collaboratively with stakeholders and partners from government and all relevant sectors.

Koirala P, Wolpin S, Phuyal P, Basnyat B, Zafren K. 2015. A Pain in the Neck. Clay shoveler's fracture due to cervical spine trauma. Wilderness Environ Med, 26 (3), pp. 430-432. | Read more

Parry CM, Thieu NTV, Dolecek C, Karkey A, Gupta R, Turner P, Dance D, Maude RR, Ha V, Tran CN et al. 2015. Clinically and microbiologically derived azithromycin susceptibility breakpoints for Salmonella enterica serovars Typhi and Paratyphi A. Antimicrob Agents Chemother, 59 (5), pp. 2756-2764. | Citations: 16 (Web of Science Lite) | Show Abstract | Read more

Azithromycin is an effective treatment for uncomplicated infections with Salmonella enterica serovar Typhi and serovar Paratyphi A (enteric fever), but there are no clinically validated MIC and disk zone size interpretative guidelines. We studied individual patient data from three randomized controlled trials (RCTs) of antimicrobial treatment in enteric fever in Vietnam, with azithromycin used in one treatment arm, to determine the relationship between azithromycin treatment response and the azithromycin MIC of the infecting isolate. We additionally compared the azithromycin MIC and the disk susceptibility zone sizes of 1,640 S. Typhi and S. Paratyphi A clinical isolates collected from seven Asian countries. In the RCTs, 214 patients who were treated with azithromycin at a dose of 10 to 20 mg/ml for 5 to 7 days were analyzed. Treatment was successful in 195 of 214 (91%) patients, with no significant difference in response (cure rate, fever clearance time) with MICs ranging from 4 to 16 μg/ml. The proportion of Asian enteric fever isolates with an MIC of ≤ 16 μg/ml was 1,452/1,460 (99.5%; 95% confidence interval [CI], 98.9 to 99.7) for S. Typhi and 207/240 (86.3%; 95% CI, 81.2 to 90.3) (P < 0.001) for S. Paratyphi A. A zone size of ≥ 13 mm to a 5-μg azithromycin disk identified S. Typhi isolates with an MIC of ≤ 16 μg/ml with a sensitivity of 99.7%. An azithromycin MIC of ≤ 16 μg/ml or disk inhibition zone size of ≥ 13 mm enabled the detection of susceptible S. Typhi isolates that respond to azithromycin treatment. Further work is needed to define the response to treatment in S. Typhi isolates with an azithromycin MIC of >16 μg/ml and to determine MIC and disk breakpoints for S. Paratyphi A.

Phuyal P, Koirala P, Basnyat B, Zafren K. 2015. An itchy situation. Wilderness Environ Med, 26 (1), pp. 89-90. | Read more

Thompson CN, Blacksell SD, Paris DH, Arjyal A, Karkey A, Dongol S, Giri A, Dolecek C, Day N, Baker S et al. 2015. Undifferentiated febrile illness in Kathmandu, Nepal. Am J Trop Med Hyg, 92 (4), pp. 875-878. | Citations: 16 (Web of Science Lite) | Show Abstract | Read more

Undifferentiated febrile illnesses (UFIs) are common in low- and middle-income countries. We prospectively investigated the causes of UFIs in 627 patients presenting to a tertiary referral hospital in Kathmandu, Nepal. Patients with microbiologically confirmed enteric fever (218 of 627; 34.8%) randomized to gatifloxacin or ofloxacin treatment were previously reported. We randomly selected 125 of 627 (20%) of these UFI patients, consisting of 96 of 409 (23%) cases with sterile blood cultures and 29 of 218 (13%) cases with enteric fever, for additional diagnostic investigations. We found serological evidence of acute murine typhus in 21 of 125 (17%) patients, with 12 of 21 (57%) patients polymerase chain reaction (PCR)-positive for Rickettsia typhi. Three UFI cases were quantitative PCR-positive for Rickettsia spp., two UFI cases were seropositive for Hantavirus, and one UFI case was seropositive for Q fever. Fever clearance time (FCT) for rickettsial infection was 44.5 hours (interquartile range = 26-66 hours), and there was no difference in FCT between ofloxacin or gatifloxacin. Murine typhus represents an important cause of predominantly urban UFIs in Nepal, and fluoroquinolones seem to be an effective empirical treatment.

Neupane M, Basnyat B, Fischer R, Froeschl G, Wolbers M, Rehfuess EA. 2015. Sustained use of biogas fuel and blood pressure among women in rural Nepal. Environ Res, 136 pp. 343-351. | Citations: 8 (Scopus) | Show Abstract | Read more

BACKGROUND: More than two fifths of the world's population cook with solid fuels and are exposed to household air pollution (HAP). As of now, no studies have assessed whether switching to alternative fuels like biogas could impact cardiovascular health among cooks previously exposed to solid fuel use. METHODS: We conducted a propensity score matched cross-sectional study to explore if the sustained use of biogas fuel for at least ten years impacts blood pressure among adult female cooks of rural Nepal. We recruited one primary cook ≥ 30 years of age from each biogas (219 cooks) and firewood (300 cooks) using household and measured their systolic (SBP) and diastolic blood pressure (DBP). Household characteristics, kitchen ventilation and 24-h kitchen carbon monoxide were assessed. We matched cooks by age, body mass index and socio-economic status score using propensity scores and investigated the effect of biogas use through multivariate regression models in two age groups, 30-50 years and >50 years to account for any post-menopausal changes. RESULTS: We found substantially reduced 24-h kitchen carbon monoxide levels among biogas-using households. After matching and adjustment for smoking, kitchen characteristics, ventilation status and additional fuel use, the use of biogas was associated with 9.8 mmHg lower SBP [95% confidence interval (CI), -20.4 to 0.8] and 6.5 mmHg lower DBP (95% CI, -12.2 to -0.8) compared to firewood users among women >50 years of age. In this age group, biogas use was also associated with 68% reduced odds [Odds ratio 0.32 (95% CI, 0.14 to 0.71)] of developing hypertension. These effects, however, were not identified in younger women aged 30-50 years. CONCLUSIONS: Sustained use of biogas for cooking may protect against cardiovascular disease by lowering the risk of high blood pressure, especially DBP, among older female cooks. These findings need to be confirmed in longitudinal or experimental studies.

Basnyat B, Baker S. 2015. Typhoid carriage in the gallbladder. Lancet, 386 (9998), pp. 1074. | Citations: 1 (Web of Science Lite) | Read more

Chung The H, Karkey A, Pham Thanh D, Boinett CJ, Cain AK, Ellington M, Baker KS, Dongol S, Thompson C, Harris SR et al. 2015. A high-resolution genomic analysis of multidrug-resistant hospital outbreaks of Klebsiella pneumoniae. EMBO Mol Med, 7 (3), pp. 227-239. | Citations: 18 (Scopus) | Show Abstract | Read more

Multidrug-resistant (MDR) Klebsiella pneumoniae has become a leading cause of nosocomial infections worldwide. Despite its prominence, little is known about the genetic diversity of K. pneumoniae in resource-poor hospital settings. Through whole-genome sequencing (WGS), we reconstructed an outbreak of MDR K. pneumoniae occurring on high-dependency wards in a hospital in Kathmandu during 2012 with a case-fatality rate of 75%. The WGS analysis permitted the identification of two MDR K. pneumoniae lineages causing distinct outbreaks within the complex endemic K. pneumoniae. Using phylogenetic reconstruction and lineage-specific PCR, our data predicted a scenario in which K. pneumoniae, circulating for 6 months before the outbreak, underwent a series of ward-specific clonal expansions after the acquisition of genes facilitating virulence and MDR. We suggest that the early detection of a specific NDM-1 containing lineage in 2011 would have alerted the high-dependency ward staff to intervene. We argue that some form of real-time genetic characterisation, alongside clade-specific PCR during an outbreak, should be factored into future healthcare infection control practices in both high- and low-income settings.

Wong VK, Baker S, Pickard DJ, Parkhill J, Page AJ, Feasey NA, Kingsley RA, Thomson NR, Keane JA, Weill F-X et al. 2015. Phylogeographical analysis of the dominant multidrug-resistant H58 clade of Salmonella Typhi identifies inter- and intracontinental transmission events. Nat Genet, 47 (6), pp. 632-639. | Citations: 79 (Scopus) | Show Abstract | Read more

The emergence of multidrug-resistant (MDR) typhoid is a major global health threat affecting many countries where the disease is endemic. Here whole-genome sequence analysis of 1,832 Salmonella enterica serovar Typhi (S. Typhi) identifies a single dominant MDR lineage, H58, that has emerged and spread throughout Asia and Africa over the last 30 years. Our analysis identifies numerous transmissions of H58, including multiple transfers from Asia to Africa and an ongoing, unrecognized MDR epidemic within Africa itself. Notably, our analysis indicates that H58 lineages are displacing antibiotic-sensitive isolates, transforming the global population structure of this pathogen. H58 isolates can harbor a complex MDR element residing either on transmissible IncHI1 plasmids or within multiple chromosomal integration sites. We also identify new mutations that define the H58 lineage. This phylogeographical analysis provides a framework to facilitate global management of MDR typhoid and is applicable to similar MDR lineages emerging in other bacterial species.

Pant S, Keyes LE, Sharma R, Basnyat B. 2015. A trekker in Nepal with painful skin blisters. BMJ Case Rep, 2015 (jun18 1), pp. bcr2015210560-bcr2015210560. | Show Abstract | Read more

The authors present a case of a 27-year-old woman trekker with painful, slightly itchy eruptions on the dorsum of both hands for 5 days. On examination, she had a papulovesicular rash with some haemorrhagic vesicles over the dorsum of her hands and thumbs.

Shrestha P, Paudyal B, Basnyat B. 2015. GeneXpert MTB/RIF assay as initial test for diagnosis of tuberculous meningitis. BMJ Case Rep, 2015 (jun11 2), pp. bcr2014207502-bcr2014207502. | Show Abstract | Read more

Tuberculous meningitis (TBM) remains the most dangerous form of tuberculosis with high mortality and potential complications. The prompt diagnosis and treatment of this condition remains a key for better prognosis. A 39-year-old woman presented with severe headache, fever, nausea and vomiting, with a history of headache for a month. On examination, confusion, neck rigidity, ptosis and upward plantar reflexes were present. After 7 days of empiric treatment without resolution of her symptoms, she had another spinal tap performed. The diagnosis of TBM was performed by the GeneXpert MTB/RIF assay from her cerebrospinal fluid (CSF). Antitubercular chemotherapy was started. The patient subsequently improved. Where available, the GeneXpert assay should be used immediately in CSF samples of patients suspected of TBM as an adjunct to clinical algorithms to increase the chance of a prompt diagnosis and treatment.

MacKinney TG, Soti KR, Shrestha P, Basnyat B. 2015. Camphor: an herbal medicine causing grand mal seizures. BMJ Case Rep, 2015 (jun11 1), pp. bcr2014209101-bcr2014209101. | Show Abstract | Read more

Camphor is usually used in the USA to repel insects, but it is widely used in other countries as an herb. We report the case of a 52-year-old previously healthy Nepali man who ingested approximately 10 g of pure camphor with therapeutic intention. He developed grand mal seizures, and was evaluated in an emergency room. He failed to recall the camphor ingestion initially, and was treated with phenytoin for new-onset idiopathic seizures. Examining physicians only later found out about his camphor ingestion. Finding the cause of new-onset seizures is often challenging for emergency room physicians, internists and neurologists. In addition to other well-reported causes of secondary seizures, herbal medications and supplements must also be explored.

Shrestha P, Arjyal A, Caws M, Prajapati KG, Karkey A, Dongol S, Pathak S, Prajapati S, Basnyat B. 2015. The Application of GeneXpert MTB/RIF for Smear-Negative TB Diagnosis as a Fee-Paying Service at a South Asian General Hospital. Tuberc Res Treat, 2015 pp. 102430. | Show Abstract | Read more

The GeneXpert MTB/RIF assay (Xpert) is a novel automated diagnostic tool for tuberculosis but its optimal placement in the healthcare system has not been determined. The objective of this study was to determine the possibility of additional case detection for pulmonary tuberculosis (PTB) by offering Xpert to smear-negative patients in a low-HIV burden setting with no Mycobacterium tuberculosis (M.tb.) culture facilities. Patients routinely presenting with symptoms suggestive of PTB with negative smears were offered single Xpert test on a fee-paying basis. Data were retrospectively reviewed to determine case detection in patients tested from February to December 2013. Symptoms associated with a positive test were analysed to determine if refinement of clinical criteria would reduce unnecessary testing. 258 smear-negative patients were included and M.tb. was detected in 55 (21.32%, n = 55/258). Using standard clinical assessment for selection, testing 5 patients detected one case of smear-negative PTB. These results demonstrate that fee-paying Xpert service in low-income setting can increase TB case confirmation substantially and further systematic studies of health economic implications should be conducted to determine optimal implementation models to increase access to Xpert in low- and middle-income countries.

Basnyat B, Baker S. 2015. Typhoid carriage in the gallbladder The Lancet, 386 (9998), pp. 1074. | Read more

Koirala P, Wolpin S, Phuyal P, Basnyat B, Zafren K. 2015. A Pain in the Neck Wilderness and Environmental Medicine, 26 (3), pp. 430-432. | Read more

Mendelson M, Røttingen J-A, Gopinathan U, Hamer DH, Wertheim H, Basnyat B, Butler C, Tomson G, Balasegaram M. 2016. Maximising access to achieve appropriate human antimicrobial use in low-income and middle-income countries. Lancet, 387 (10014), pp. 188-198. | Citations: 25 (Web of Science Lite) | Show Abstract | Read more

Access to quality-assured antimicrobials is regarded as part of the human right to health, yet universal access is often undermined in low-income and middle-income countries. Lack of access to the instruments necessary to make the correct diagnosis and prescribe antimicrobials appropriately, in addition to weak health systems, heightens the challenge faced by prescribers. Evidence-based interventions in community and health-care settings can increase access to appropriately prescribed antimicrobials. The key global enablers of sustainable financing, governance, and leadership will be necessary to achieve access while preventing excess antimicrobial use.

Basnyat B, Tabin C, Nutt C, Farmer P. 2015. Post-earthquake Nepal: the way forward. Lancet Glob Health, 3 (12), pp. e731-e732. | Citations: 7 (Web of Science Lite) | Read more

Basnyat B. 2014. Rebuttal to the con statement. High Alt Med Biol, 15 (4), pp. 444. | Read more

Basnyat B. 2014. Pro: pulse oximetry is useful in predicting acute mountain sickness. High Alt Med Biol, 15 (4), pp. 440-441. | Citations: 4 (Web of Science Lite) | Read more

Basnyat B. 2014. High altitude pilgrimage medicine. High Alt Med Biol, 15 (4), pp. 434-439. | Citations: 8 (Scopus) | Show Abstract | Read more

Religious pilgrims have been going to high altitude pilgrimages long before trekkers and climbers sojourned in high altitude regions, but the medical literature about high altitude pilgrimage is sparse. Gosainkunda Lake (4300 m) near Kathmandu, Nepal, and Shri Amarnath Yatra (3800 m) in Sri Nagar, Kashmir, India, are the two sites in the Himalayas from where the majority of published reports of high altitude pilgrimage have originated. Almost all travels to high altitude pilgrimages are characterized by very rapid ascents by large congregations, leading to high rates of acute mountain sickness (AMS). In addition, epidemiological studies of pilgrims from Gosainkunda Lake show that some of the important risk factors for AMS in pilgrims are female sex and older age group. Studies based on the Shri Amarnath Yatra pilgrims show that coronary artery disease, complications of diabetes, and peptic ulcer disease are some of the common, important reasons for admission to hospital during the trip. In this review, the studies that have reported these and other relevant findings will be discussed and appropriate suggestions made to improve pilgrims' safety at high altitude.

Basnyat B. 2014. High Altitude Pilgrimage Medicine HIGH ALTITUDE MEDICINE & BIOLOGY, 15 (4), pp. 434-439. | Citations: 9 (Web of Science Lite) | Read more

Bruno RM, Cogo A, Ghiadoni L, Duo E, Pomidori L, Sharma R, Thapa GB, Basnyat B, Bartesaghi M, Picano E et al. 2014. Cardiovascular function in healthy Himalayan high-altitude dwellers. Atherosclerosis, 236 (1), pp. 47-53. | Citations: 9 (Scopus) | Show Abstract | Read more

BACKGROUND: Residents of the Himalayan valleys uniquely adapted to their hypoxic environment in terms of pulmonary vasculature, but their systemic vascular function is still largely unexplored. The aim of the study was to investigate vascular function and structure in rural Sherpa population, permanently living at high altitude in Nepal (HA), in comparison with control Caucasian subjects (C) living at sea level. METHODS AND RESULTS: 95 HA and 64 C were enrolled. Cardiac ultrasound, flow-mediated dilation (FMD) of the brachial artery, carotid geometry and stiffness, and aortic pulse wave velocity (PWV) were performed. The same protocol was repeated in 11 HA with reduced FMD, after 1-h 100% O2 administration. HA presented lower FMD (5.18 ± 3.10 vs. 6.44  ±  2.91%, p = 0.02) and hyperemic velocity than C (0.61 ± 0.24 vs. 0.75 ± 0.28 m/s, p = 0.008), while systolic pulmonary pressure was higher (29.4 ± 5.5 vs. 23.6 ± 4.8 mmHg, p < 0.0001). In multiple regression analysis performed in HA, hyperemic velocity remained an independent predictor of FMD, after adjustment for baseline brachial artery diameter, room temperature and pulse pressure, explaining 8.7% of its variance. On the contrary, in C brachial artery diameter remained the only independent predictor of FMD, after adjustment for confounders. HA presented also lower carotid IMT than C (0.509 ± 0.121 vs. 0.576 ± 0.122 mm, p < 0.0001), higher diameter (6.98 ± 1.07 vs. 6.81 ± 0.85 mm, p = 0.004 adjusted for body surface area) and circumferential wall stress (67.6 ± 13.1 vs. 56.4 ± 16.0 kPa, p < 0.0001), while PWV was similar. O2 administration did not modify vascular variables. CONCLUSIONS: HA exhibit reduced NO-mediated dilation in the brachial artery, which is associated to reduced hyperemic response, indicating microcirculatory dysfunction. A peculiar carotid phenotype, characterized by reduced IMT and enlarged diameter, was also found.

Basnyat B. 2014. Antibiotic resistance needs global solutions. Lancet Infect Dis, 14 (7), pp. 549-550. | Citations: 4 (Scopus) | Read more

Näsström E, Vu Thieu NT, Dongol S, Karkey A, Voong Vinh P, Ha Thanh T, Johansson A, Arjyal A, Thwaites G, Dolecek C et al. 2014. Salmonella Typhi and Salmonella Paratyphi A elaborate distinct systemic metabolite signatures during enteric fever. Elife, 3 | Citations: 15 (Web of Science Lite) | Show Abstract | Read more

The host-pathogen interactions induced by Salmonella Typhi and Salmonella Paratyphi A during enteric fever are poorly understood. This knowledge gap, and the human restricted nature of these bacteria, limit our understanding of the disease and impede the development of new diagnostic approaches. To investigate metabolite signals associated with enteric fever we performed two dimensional gas chromatography with time-of-flight mass spectrometry (GCxGC/TOFMS) on plasma from patients with S. Typhi and S. Paratyphi A infections and asymptomatic controls, identifying 695 individual metabolite peaks. Applying supervised pattern recognition, we found highly significant and reproducible metabolite profiles separating S. Typhi cases, S. Paratyphi A cases, and controls, calculating that a combination of six metabolites could accurately define the etiological agent. For the first time we show that reproducible and serovar specific systemic biomarkers can be detected during enteric fever. Our work defines several biologically plausible metabolites that can be used to detect enteric fever, and unlocks the potential of this method in diagnosing other systemic bacterial infections.

Maeder MMB, Basnyat B, Harris NS. 2014. From Matterhorn to Mt Everest: empowering rescuers and improving medical care in Nepal. Wilderness Environ Med, 25 (2), pp. 177-181. | Citations: 1 (Scopus) | Show Abstract | Read more

This article describes a private initiative in which professional Swiss rescuers, based at the foot of the Matterhorn, trained Nepalese colleagues in advanced high altitude helicopter rescue and medical care techniques. What started as a limited program focused on mountain safety has rapidly developed into a comprehensive project to improve rescue and medical care in the Mt Everest area for both foreign travelers and the local Nepalese people.

Childs G, Craig S, Beall CM, Basnyat B. 2014. Depopulating the Himalayan Highlands: Education and Outmigration From Ethnically Tibetan Communities of Nepal MOUNTAIN RESEARCH AND DEVELOPMENT, 34 (2), pp. 85-94. | Citations: 9 (Scopus) | Show Abstract | Read more

Communities that have thrived for centuries in Nepal's rugged mountain environments are facing rapid population declines caused by the outmigration of youths, both males and females in nearly equal numbers, who are sent by parents to distant boarding schools and monasteries for secular and religious education. This paper documents the magnitude of outmigration, migration destinations, migration's impact on the age-sex composition of sending communities, the effect of migration on fertility, and projected trends of population decline and aging. The authors conclude by discussing potential long-term threats to the viability of ethnically Tibetan communities in the Himalayan highlands, including outmigration's effect on agricultural production, the family-based care system for the elderly, socioeconomic inequalities, and human capital. © 2014 by the authors.

Thapa GB, Neupane M, Strapazzon G, Basnyat B, Elsenshon F, Brodmann Maeder M, Brugger H. 2014. Nepalese mountain rescue development project. High Alt Med Biol, 15 (1), pp. 91-92. | Read more

Dunstan SJ, Hue NT, Han B, Li Z, Tram TTB, Sim KS, Parry CM, Chinh NT, Vinh H, Lan NPH et al. 2014. Variation at HLA-DRB1 is associated with resistance to enteric fever. Nat Genet, 46 (12), pp. 1333-1336. | Citations: 22 (Web of Science Lite) | Show Abstract | Read more

Enteric fever affects more than 25 million people annually and results from systemic infection with Salmonella enterica serovar Typhi or Paratyphi pathovars A, B or C(1). We conducted a genome-wide association study of 432 individuals with blood culture-confirmed enteric fever and 2,011 controls from Vietnam. We observed strong association at rs7765379 (odds ratio (OR) for the minor allele = 0.18, P = 4.5 × 10(-10)), a marker mapping to the HLA class II region, in proximity to HLA-DQB1 and HLA-DRB1. We replicated this association in 595 enteric fever cases and 386 controls from Nepal and also in a second independent collection of 151 cases and 668 controls from Vietnam. Imputation-based fine-mapping across the extended MHC region showed that the classical HLA-DRB1*04:05 allele (OR = 0.14, P = 2.60 × 10(-11)) could entirely explain the association at rs7765379, thus implicating HLA-DRB1 as a major contributor to resistance against enteric fever, presumably through antigen presentation.

Shrestha P, Pun M, Basnyat B. 2014. High altitude pulmonary edema (HAPE) in a Himalayan trekker: a case report. Extrem Physiol Med, 3 (1), pp. 6. | Citations: 2 (Scopus) | Show Abstract | Read more

INTRODUCTION: High altitude pulmonary edema is a non-cardiogenic form of pulmonary edema that develops in unacclimatized individuals at altitudes over 2500 m. Early recognition of symptoms and immediate descent are important for successful treatment. Despite early signs and symptoms of high altitude illness, many trekkers tend to push themselves to the maximum limit. Some of them, such as the case reported here, choose to ascend on horse-back which is extremely dangerous and can be fatal. CASE PRESENTATION: A 55 years of age Indian ethnic South African lady was emergency air-lifted from 4410 m altitude in the Nepal Himalayas to Kathamandu (1300 m) with a suspected case of high altitude pulmonary edema. She had continued ascending despite experiencing mild altitude symptoms at Namche (3440 m), and these symptoms worsened considerably at Tengboche (3860 m). At the very start of her trek, just after Lukla (2800 m), she suffered from sore throat, and had consequently begun a course of antibiotics (azithromycin) for a suspected throat infection. She had planned to continue ascending on horse back to complete the trek, however her condition deteriorated further and she had to be medically evacuated.On admission to the clinic her axillary temperature was 99.4 F, blood pressure 120/60 mmHg, pulse rate 72/min, respiratory rate of 25 breaths/min, and pulse oximeter showed saturation of 90% on room air at rest. Right sided crackles on the axillary and posterior region were heard on chest auscultation. Heel to toe test showed no signs of ataxia. The chest radiograph showed patchy infiltrates on the right side. An echocardiogram was done which revealed a high pulmonary artery pressure of 50 mm of Hg. She was diagnosed as resolving high altitude pulmornay edema. She was treated with bed rest, supplemental oxygen and sustained release nifedipine 20 mg (orally) twice a day. On the third day her crackles had cleared significantly and repeat chest radiograph as shown showed remarkable improvement. She felt much better. A repeat echocardiogram revealed a normal pulmonary artery pressure. CONCLUSION: The case report highlights numerous points:1) Many high altitude trekkers have invested significant time, money and physical efforts in in their ventures and are determined to ascend despite early warning and illnesses. 2) Despite no history of altitude illnesses in previous altitude exposure,inter-current illness (in this case a nonspecific respiratory tract infection) may contribute to the development of high altitude pulmonary edema. 3) Continuing ascent using other transport means, whilst suffering from symptoms of high altitude illness, worsens the condition and could be life threatening. 4) Acetazolamide does not prevent high altitude pulmonary edema-perhaps more so in the cases that have inter-current illness. 5) Descent is the golden rule in all altitude illnesses. Actually 'descent' is advised in any undiagnosed illness at high altitude among sojourners. 6) Finally, an experienced guide who has mountain medicine training is essential. They can be crucial in noticing early signs and symptoms of altitude illnesses to inform the client's safety as in this case.

Jeong C, Alkorta-Aranburu G, Basnyat B, Neupane M, Witonsky DB, Pritchard JK, Beall CM, Di Rienzo A. 2014. Admixture facilitates genetic adaptations to high altitude in Tibet. Nat Commun, 5 pp. 3281. | Citations: 67 (Web of Science Lite) | Show Abstract | Read more

Admixture is recognized as a widespread feature of human populations, renewing interest in the possibility that genetic exchange can facilitate adaptations to new environments. Studies of Tibetans revealed candidates for high-altitude adaptations in the EGLN1 and EPAS1 genes, associated with lower haemoglobin concentration. However, the history of these variants or that of Tibetans remains poorly understood. Here we analyse genotype data for the Nepalese Sherpa, and find that Tibetans are a mixture of ancestral populations related to the Sherpa and Han Chinese. EGLN1 and EPAS1 genes show a striking enrichment of high-altitude ancestry in the Tibetan genome, indicating that migrants from low altitude acquired adaptive alleles from the highlanders. Accordingly, the Sherpa and Tibetans share adaptive haemoglobin traits. This admixture-mediated adaptation shares important features with adaptive introgression. Therefore, we identify a novel mechanism, beyond selection on new mutations or on standing variation, through which populations can adapt to local environments.

Basnyat B. 2014. Letters: On India, offshore accounts, climate change, Japan, illegal booze, SWAT teams Economist (United Kingdom), 410 (8879),

Panthi S, Basnyat B. 2013. High altitude pulmonary oedema (HAPE) in an Indian pilgrim. J Assoc Physicians India, 61 (11), pp. 846-848. | Show Abstract

Increasing number of Hindu pilgrims visit the Himalayas where some of them suffer from high altitude illness including the life threatening forms, high altitude pulmonary oedema (HAPE) and high altitude cerebral oedema. Compared to tourists and trekkers, pilgrims are usually ignorant about altitude illness. This is a case of a pilgrim who suffered from HAPE on his trip to Kailash-Mansarovar and is brought to a tertiary level hospital in Kathmandu. This report emphasises on how to treat a patient with HAPE, a disease which is increasingly being seen in the high altitude pilgrim population.

Panthi S, Basnyat B. 2013. High altitude pulmonary oedema (HAPE) in an Indian pilgrim Journal of Association of Physicians of India, 61 (NOV), pp. 846-848. | Citations: 1 (Scopus) | Show Abstract

Increasing number of Hindu pilgrims visit the Himalayas where some of them suffer from high altitude illness including the life threatening forms, high altitude pulmonary oedema (HAPE) and high altitude cerebral oedema. Compared to tourists and trekkers, pilgrims are usually ignorant about altitude illness. This is a case of a pilgrim who suffered from HAPE on his trip to Kailash-Mansarovar and is brought to a tertiary level hospital in Kathmandu. This report emphasises on how to treat a patient with HAPE, a disease which is increasingly being seen in the high altitude pilgrim population. © JAPI.

Basnyat B. 2013. Acute High-Altitude Illnesses New England Journal of Medicine, 369 (17), pp. 1664-1667. | Citations: 16 (Scopus) | Read more

Basnyat B. 2013. Acute high-altitude illnesses. N Engl J Med, 369 (17), pp. 1666. | Read more

Johnson PL, Johnson CC, Poudyal P, Regmi N, Walmsley MA, Basnyat B. 2013. Continuous positive airway pressure treatment for acute mountain sickness at 4240 m in the Nepal Himalaya. High Alt Med Biol, 14 (3), pp. 230-233. | Citations: 4 (Scopus) | Show Abstract | Read more

Acute mountain sickness (AMS) is very common at altitudes above 2500 m. There are few treatment options in the field where electricity availability is limited, and medical assistance or oxygen is unavailable or difficult to access. Positive airway pressure has been used to treat AMS at 3800 m. We hypothesized that continuous positive airway pressure (CPAP) could be used under field conditions powered by small rechargeable batteries. Methods Part 1. 5 subjects trekked to 3500 m from 2800 m in one day and slept there for one night, ascending in the late afternoon to 3840 m, where they slept using CPAP 6-7 cm via mask. The next morning they descended to 3500 m, spent the day there, ascended in late afternoon to 3840 m, and slept the night without CPAP. Continuous overnight oximetry was recorded and the Lake Louise questionnaire for AMS administered both mornings. Methods Part 2. 14 trekkers with symptoms of AMS were recruited at 4240 m. All took acetazolamide. The Lake Louise questionnaire was administered, oximetry recorded, and CPAP 6-7 cm was applied for 10-15 min. CPAP was used overnight and oximetry recorded continuously. In the morning the Lake Louise questionnaire was administered, and oximetry recorded for 10-15 min. The equipment used in both parts was heated, humidified Respironics RemStar® machines powered by Novuscell™ rechargeable lithium ion batteries. Oximetry was recorded using Embletta™ PDS. Results Part 1. CPAP improved overnight Sao2 and eliminated AMS symptoms in the one subject who developed AMS. CPAP was used for 7-9 h and the machines operated for >8 h using the battery. Results Part 2. CPAP use improved Sao2 when used for 10-15 min at the time of recruitment and overnight CPAP use resulted in significantly reduced AMS symptoms. Conclusion. CPAP with rechargeable battery may be a useful treatment option for trekkers and climbers who develop AMS.

Basnyat B. 2013. Rebuttal to pro statements. High Alt Med Biol, 14 (3), pp. 219. | Citations: 1 (Scopus) | Read more

Basnyat B. 2013. Con: All dwellers at high altitude are persons of impaired physical and mental powers: the view from the Himalayas. High Alt Med Biol, 14 (3), pp. 214-215. | Citations: 1 (Web of Science Lite) | Read more

Tanner JB, Tanner SME, Thapa GB, Chang Y, Watson KLM, Staunton E, Howarth C, Basnyat B, Harris NS. 2013. A randomized trial of temazepam versus acetazolamide in high altitude sleep disturbance. High Alt Med Biol, 14 (3), pp. 234-239. | Citations: 5 (Scopus) | Show Abstract | Read more

This study is the first comparative trial of sleep medications at high altitude. We performed a randomized, double-blind trial of temazepam and acetazolamide at an altitude of 3540 meters. 34 healthy trekkers with self-reports of high-altitude sleep disturbance were randomized to temazepam 7.5 mg or acetazolamide 125 mg taken at bedtime for one night. The primary outcome was sleep quality on a 100 mm visual analog scale. Additional measurements were obtained with actigraphy; pulse oximetry; and questionnaire evaluation of sleep, daytime drowsiness, daytime sleepiness, and acute mountain sickness. Sixteen subjects were randomized to temazepam and 18 to acetazolamide. Sleep quality on the 100 mm visual analog scale was higher for temazepam (59.6, SD 20.1) than acetazolamide (46.2, SD 20.2; p=0.048). Temazepam also demonstrated higher subjective sleep quality on the Groningen Sleep Quality Scale (3.5 vs. 6.8, p=0.009) and sleep depth visual analog scale (60.3 vs. 41.4, p=0.028). The acetazolamide group reported significantly more awakenings to urinate (1.8 vs. 0.5, p=0.007). No difference was found with regards to mean nocturnal oxygen saturation (84.1 vs. 84.4, p=0.57), proportion of the night spent in periodic breathing, relative desaturations, sleep onset latency, awakenings, wake after sleep onset, sleep efficiency, Stanford Sleepiness Scale scores, daytime drowsiness, or change in self-reported Lake Louise Acute Mountain Sickness scores. We conclude that, at current recommended dosing, treatment of high-altitude sleep disturbance with temazepam is associated with increased subjective sleep quality compared to acetazolamide.

Giri A, Arjyal A, Koirala S, Karkey A, Dongol S, Thapa SD, Shilpakar O, Shrestha R, van Tan L, Thi Thuy Chinh BN et al. 2013. Aetiologies of central nervous system infections in adults in Kathmandu, Nepal: a prospective hospital-based study. Sci Rep, 3 (1), pp. 2382. | Citations: 8 (Scopus) | Show Abstract | Read more

We conducted a prospective hospital based study from February 2009-April 2011 to identify the possible pathogens of central nervous system (CNS) infections in adults admitted to a tertiary referral hospital (Patan Hospital) in Kathmandu, Nepal. The pathogens of CNS infections were confirmed in cerebrospinal fluid (CSF) using molecular diagnostics, culture (bacteria) and serology. 87 patients were recruited for the study and the etiological diagnosis was established in 38% (n = 33). The bacterial pathogens identified were Neisseria meningitidis (n = 6); Streptococcus pneumoniae (n = 5) and Staphylococcus aureus (n = 2) in 13/87(14%). Enteroviruses were found in 12/87 (13%); Herpes Simplex virus (HSV) in 2/87(2%). IgM against Japanese encephalitis virus (JEV) was detected in the CSF of 11/73 (15%) tested samples. This is the first prospective molecular and serology based CSF analysis in adults with CNS infections in Kathmandu, Nepal. JEV and enteroviruses were the most commonly detected pathogens in this setting.

Charles RC, Sultana T, Alam MM, Yu Y, Wu-Freeman Y, Bufano MK, Rollins SM, Tsai L, Harris JB, LaRocque RC et al. 2013. Identification of immunogenic Salmonella enterica serotype Typhi antigens expressed in chronic biliary carriers of S. Typhi in Kathmandu, Nepal. PLoS Negl Trop Dis, 7 (8), pp. e2335. | Citations: 11 (Scopus) | Show Abstract | Read more

BACKGROUND: Salmonella enterica serotype Typhi can colonize and persist in the biliary tract of infected individuals, resulting in a state of asymptomatic chronic carriage. Chronic carriers may act as persistent reservoirs of infection within a community and may introduce infection to susceptible individuals and new communities. Little is known about the interaction between the host and pathogen in the biliary tract of chronic carriers, and there is currently no reliable diagnostic assay to identify asymptomatic S. Typhi carriage. METHODOLOGY/PRINCIPAL FINDINGS: To study host-pathogen interactions in the biliary tract during S. Typhi carriage, we applied an immunoscreening technique called in vivo-induced antigen technology (IVIAT), to identify potential biomarkers unique to carriers. IVIAT identifies humorally immunogenic bacterial antigens expressed uniquely in the in vivo environment, and we hypothesized that S. Typhi surviving in the biliary tract of humans may express a distinct antigenic profile. Thirteen S. Typhi antigens that were immunoreactive in carriers, but not in healthy individuals from a typhoid endemic area, were identified. The identified antigens included a number of putative membrane proteins, lipoproteins, and hemolysin-related proteins. YncE (STY1479), an uncharacterized protein with an ATP-binding motif, gave prominent responses in our screen. The response to YncE in patients whose biliary tract contained S. Typhi was compared to responses in patients whose biliary tract did not contain S. Typhi, patients with acute typhoid fever, and healthy controls residing in a typhoid endemic area. Seven of 10 (70%) chronic carriers, 0 of 8 bile culture-negative controls (0%), 0 of 8 healthy Bangladeshis (0%), and 1 of 8 (12.5%) Bangladeshis with acute typhoid fever had detectable anti-YncE IgG in blood. IgA responses were also present. CONCLUSIONS/SIGNIFICANCE: Further evaluation of YncE and other antigens identified by IVIAT could lead to the development of improved diagnostic assays to identify asymptomatic S. Typhi carriers.

Andrews JR, Prajapati KG, Eypper E, Shrestha P, Shakya M, Pathak KR, Joshi N, Tiwari P, Risal M, Koirala S et al. 2013. Evaluation of an electricity-free, culture-based approach for detecting typhoidal Salmonella bacteremia during enteric fever in a high burden, resource-limited setting. PLoS Negl Trop Dis, 7 (6), pp. e2292. | Citations: 9 (Web of Science Lite) | Show Abstract | Read more

BACKGROUND: In many rural areas at risk for enteric fever, there are few data on Salmonella enterica serotypes Typhi (S. Typhi) and Paratyphi (S. Paratyphi) incidence, due to limited laboratory capacity for microbiologic culture. Here, we describe an approach that permits recovery of the causative agents of enteric fever in such settings. This approach involves the use of an electricity-free incubator based upon use of phase-change materials. We compared this against conventional blood culture for detection of typhoidal Salmonella. METHODOLOGY/PRINCIPAL FINDINGS: Three hundred and four patients with undifferentiated fever attending the outpatient and emergency departments of a public hospital in the Kathmandu Valley of Nepal were recruited. Conventional blood culture was compared against an electricity-free culture approach. Blood from 66 (21.7%) patients tested positive for a Gram-negative bacterium by at least one of the two methods. Sixty-five (21.4%) patients tested blood culture positive for S. Typhi (30; 9.9%) or S. Paratyphi A (35; 11.5%). From the 65 individuals with culture-confirmed enteric fever, 55 (84.6%) were identified by the conventional blood culture and 60 (92.3%) were identified by the experimental method. Median time-to-positivity was 2 days for both procedures. The experimental approach was falsely positive due to probable skin contaminants in 2 of 239 individuals (0.8%). The percentages of positive and negative agreement for diagnosis of enteric fever were 90.9% (95% CI: 80.0%-97.0%) and 96.0% (92.7%-98.1%), respectively. After initial incubation, Salmonella isolates could be readily recovered from blood culture bottles maintained at room temperature for six months. CONCLUSIONS/SIGNIFICANCE: A simple culture approach based upon a phase-change incubator can be used to isolate agents of enteric fever. This approach could be used as a surveillance tool to assess incidence and drug resistance of the etiologic agents of enteric fever in settings without reliable local access to electricity or local diagnostic microbiology laboratories.

Gertsch JH, Holck PS, Basnyat B, Corbett BM. 2013. In reply to "ibuprofen for prevention of acute mountain sickness-is bigger really better?". Wilderness Environ Med, 24 (2), pp. 178-179. | Read more

Basnyat B. 2013. Rejuvenation time. High Alt Med Biol, 14 (1), pp. 1-2. | Citations: 1 (Scopus) | Read more

Karkey A, Thompson CN, Tran Vu Thieu N, Dongol S, Le Thi Phuong T, Voong Vinh P, Arjyal A, Martin LB, Rondini S, Farrar JJ et al. 2013. Differential epidemiology of Salmonella Typhi and Paratyphi A in Kathmandu, Nepal: a matched case control investigation in a highly endemic enteric fever setting. PLoS Negl Trop Dis, 7 (8), pp. e2391. | Citations: 26 (Scopus) | Show Abstract | Read more

BACKGROUND: Enteric fever, a systemic infection caused by the bacteria Salmonella Typhi and Salmonella Paratyphi A, is endemic in Kathmandu, Nepal. Previous work identified proximity to poor quality water sources as a community-level risk for infection. Here, we sought to examine individual-level risk factors related to hygiene and sanitation to improve our understanding of the epidemiology of enteric fever in this setting. METHODOLOGY AND PRINCIPAL FINDINGS: A matched case-control analysis was performed through enrollment of 103 blood culture positive enteric fever patients and 294 afebrile community-based age and gender-matched controls. A detailed questionnaire was administered to both cases and controls and the association between enteric fever infection and potential exposures were examined through conditional logistic regression. Several behavioral practices were identified as protective against infection with enteric fever, including water storage and hygienic habits. Additionally, we found that exposures related to poor water and socioeconomic status are more influential in the risk of infection with S. Typhi, whereas food consumption habits and migration play more of a role in risk of S. Paratyphi A infection. CONCLUSIONS AND SIGNIFICANCE: Our work suggests that S. Typhi and S. Paratyphi A follow different routes of infection in this highly endemic setting and that sustained exposure to both serovars probably leads to the development of passive immunity. In the absence of a polyvalent vaccine against S. Typhi and S. Paratyphi A, we advocate better systems for water treatment and storage, improvements in the quality of street food, and vaccination with currently available S. Typhi vaccines.

Koirala S, Basnyat B, Arjyal A, Shilpakar O, Shrestha K, Shrestha R, Shrestha UM, Agrawal K, Koirala KD, Thapa SD et al. 2013. Gatifloxacin versus ofloxacin for the treatment of uncomplicated enteric fever in Nepal: an open-label, randomized, controlled trial. PLoS Negl Trop Dis, 7 (10), pp. e2523. | Citations: 14 (Scopus) | Show Abstract | Read more

BACKGROUND: Fluoroquinolones are the most commonly used group of antimicrobials for the treatment of enteric fever, but no direct comparison between two fluoroquinolones has been performed in a large randomised trial. An open-label randomized trial was conducted to investigate whether gatifloxacin is more effective than ofloxacin in the treatment of uncomplicated enteric fever caused by nalidixic acid-resistant Salmonella enterica serovars Typhi and Paratyphi A. METHODOLOGY AND PRINCIPAL FINDINGS: Adults and children clinically diagnosed with uncomplicated enteric fever were enrolled in the study to receive gatifloxacin (10 mg/kg/day) in a single dose or ofloxacin (20 mg/kg/day) in two divided doses for 7 days. Patients were followed for six months. The primary outcome was treatment failure in patients infected with nalidixic acid resistant isolates. 627 patients with a median age of 17 (IQR 9-23) years were randomised. Of the 218 patients with culture confirmed enteric fever, 170 patients were infected with nalidixic acid-resistant isolates. In the ofloxacin group, 6 out of 83 patients had treatment failure compared to 5 out of 87 in the gatifloxacin group (hazard ratio [HR] of time to failure 0.81, 95% CI 0.25 to 2.65, p = 0.73). The median time to fever clearance was 4.70 days (IQR 2.98-5.90) in the ofloxacin group versus 3.31 days (IQR 2.29-4.75) in the gatifloxacin group (HR = 1.59, 95% CI 1.16 to 2.18, p = 0.004). The results in all blood culture-confirmed patients and all randomized patients were comparable. CONCLUSION: Gatifloxacin was not superior to ofloxacin in preventing failure, but use of gatifloxacin did result in more prompt fever clearance time compared to ofloxacin. TRIAL REGISTRATION: ISRCTN 63006567 (www.controlled-trials.com).

Parry CM, Basnyat B, Crump JA. 2013. The management of antimicrobial-resistant enteric fever. Expert Rev Anti Infect Ther, 11 (12), pp. 1259-1261. | Citations: 8 (Web of Science Lite) | Read more

Pun M, Basnyat B. 2013. International hypoxia symposium XVIII: 26 February-02 March 2013. Extrem Physiol Med, 2 (1), pp. 32. | Show Abstract | Read more

The 18th International Hypoxia Symposia, Lake Louise, Alberta, Canada, February 26-March 02, 2013, covered molecular basis of hypoxic responses (e.g., hypoxia inducible factor, nitrite, nitrate, and hemoglobin) and integrative physiology (e.g., exercise physiology, cerebral blood flow responses, live-high train-low, and population genetics). Free communications and poster sessions covered scientific areas from controlled lab settings to field settings of high altitudes (Andes to Himalayas).

Ramachandran S, Singhal M, McKenzie KG, Osborn JL, Arjyal A, Dongol S, Baker SG, Basnyat B, Farrar J, Dolecek C et al. 2013. A Rapid, Multiplexed, High-Throughput Flow-Through Membrane Immunoassay: A Convenient Alternative to ELISA. Diagnostics (Basel), 3 (2), pp. 244-260. | Show Abstract | Read more

This paper describes a rapid, high-throughput flow-through membrane immunoassay (FMIA) platform. A nitrocellulose membrane was spotted in an array format with multiple capture and control reagents for each sample detection area, and assay steps were carried out by sequential aspiration of sample and reagents through each detection area using a 96-well vacuum manifold. The FMIA provides an alternate assay format with several advantages over ELISA. The high surface area of the membrane permits high label concentration using gold labels, and the small pores and vacuum control provide rapid diffusion to reduce total assay time to ~30 min. All reagents used in the FMIA are compatible with dry storage without refrigeration. The results appear as colored spots on the membrane that can be quantified using a flatbed scanner. We demonstrate the platform for detection of IgM specific to lipopolysaccharides (LPS) derived from Salmonella Typhi. The FMIA format provides analytical results comparable to ELISA in less time, provides integrated assay controls, and allows compensation for specimen-to-specimen variability in background, which is a particular challenge for IgM assays.

Basnyat B. 2012. Acclimatizing with acetazolamide. J Travel Med, 19 (5), pp. 281-283. | Citations: 3 (Web of Science Lite) | Read more

Cushing TA, McIntosh SE, Keyes LE, Rodway GW, Schoene RB, Basnyat B, Freer L. 2012. Performance-enhancing drugs-commentaries. Wilderness Environ Med, 23 (3), pp. 207-211. | Citations: 5 (Scopus) | Read more

Shrestha P, Basnyat B, Küpper T, van der Giet S. 2012. Cerebral venous sinus thrombosis at high altitude. High Alt Med Biol, 13 (1), pp. 60-62. | Citations: 4 (Web of Science Lite) | Show Abstract | Read more

Cerebral venous sinus thrombosis (CVST) is a rare but potentially life-threatening medical condition. We describe a case of a 47-year-old woman who presented with headache, speech defects, and visual disturbances, and was later diagnosed with cerebral venous sinus thrombosis. The article describes a possible risk of such thrombotic events with exposure to high altitude environment in patients with coagulation defects such as Factor V Leiden mutation. Besides, such neurological conditions can occur independent of altitude illness and need to be recognized as their management differs.

Koirala KD, Thanh DP, Thapa SD, Arjyal A, Karkey A, Dongol S, Shrestha UM, Farrar JJ, Basnyat B, Baker S. 2012. Highly resistant Salmonella enterica serovar Typhi with a novel gyrA mutation raises questions about the long-term efficacy of older fluoroquinolones for treating typhoid fever. Antimicrob Agents Chemother, 56 (5), pp. 2761-2762. | Citations: 20 (Scopus) | Show Abstract | Read more

As a consequence of multidrug resistance, clinicians are highly dependent on fluoroquinolones for treating the serious systemic infection typhoid fever. While reduced susceptibility to fluoroquinolones, which lessens clinical efficacy, is becoming ubiquitous, comprehensive resistance is exceptional. Here we report ofloxacin treatment failure in typhoidal patient infected with a novel, highly fluoroquinolone-resistant isolate of Salmonella enterica serovar Typhi. The isolation of this organism has serious implications for the long-term efficacy of ciprofloxacin and ofloxacin for typhoid treatment.

Dongol S, Thompson CN, Clare S, Nga TVT, Duy PT, Karkey A, Arjyal A, Koirala S, Khatri NS, Maskey P et al. 2012. The microbiological and clinical characteristics of invasive salmonella in gallbladders from cholecystectomy patients in kathmandu, Nepal. PLoS One, 7 (10), pp. e47342. | Citations: 25 (Scopus) | Show Abstract | Read more

Gallbladder carriage of invasive Salmonella is considered fundamental in sustaining typhoid fever transmission. Bile and tissue was obtained from 1,377 individuals undergoing cholecystectomy in Kathmandu to investigate the prevalence, characteristics and relevance of invasive Salmonella in the gallbladder in an endemic area. Twenty percent of bile samples contained a Gram-negative organism, with Salmonella Typhi and Salmonella Paratyphi A isolated from 24 and 22 individuals, respectively. Gallbladders that contained Salmonella were more likely to show evidence of acute inflammation with extensive neutrophil infiltrate than those without Salmonella, corresponding with higher neutrophil and lower lymphocyte counts in the blood of Salmonella positive individuals. Antimicrobial resistance in the invasive Salmonella isolates was limited, indicating that gallbladder colonization is unlikely to be driven by antimicrobial resistance. The overall role of invasive Salmonella carriage in the gallbladder is not understood; here we show that 3.5% of individuals undergoing cholecystectomy in this setting have a high concentration of antimicrobial sensitive, invasive Salmonella in their bile. We predict that such individuals will become increasingly important if current transmission mechanisms are disturbed; prospectively identifying these individuals is, therefore, paramount for rapid local and regional elimination.

Gertsch JH, Corbett B, Holck PS, Mulcahy A, Watts M, Stillwagon NT, Casto AM, Abramson CH, Vaughan CPA, Macguire C et al. 2012. Altitude Sickness in Climbers and Efficacy of NSAIDs Trial (ASCENT): randomized, controlled trial of ibuprofen versus placebo for prevention of altitude illness. Wilderness Environ Med, 23 (4), pp. 307-315. | Citations: 21 (Web of Science Lite) | Show Abstract | Read more

OBJECTIVE: To study the effectiveness of ibuprofen versus placebo in preventing acute mountain sickness (AMS) and high altitude headache (HAH). METHODS: Double-blind, randomized, placebo-controlled trial. RESULTS: Two hundred ninety-four healthy Western trekkers were recruited on the Everest approach at 4280 m or 4358 m and randomly assigned to receive either 600 mg of ibuprofen or placebo 3 times daily before and during ascent to 4928 m. One hundred eighty-three of 294 participants completed the trial. Of the participants who did not complete the trial, 62 were lost to follow-up and another 49 broke trial protocol. In an intent-to-treat analysis (232 participants), ibuprofen was found to be more effective than placebo in reducing the incidence of AMS (24.4% vs 40.4%; P = .01) and the incidence of HAH (42.3% vs 60.5%; P < .01). Ibuprofen was also superior to placebo in reducing the severity of HAH (4.9% vs 14.7%; P = .01). The end point of oxygen saturation was also higher in the ibuprofen group (80.8 % vs 82.4%; P = .035). For the 183 participants who completed the trial and conformed to the protocol, the incidence of AMS between placebo and treatment groups was not significant (32.9% vs 22.7%; P = .129 for AMS incidence, 9.6% vs 8.2%; P = .74 for AMS severity, 54.8% vs 42.7%; P = .11 for HAH incidence, and 8.2% vs 3.6%; P = .18 for HAH severity). CONCLUSIONS: Ibuprofen was found to be effective in preventing AMS in the intent-to-treat analysis group but not in those who completed the trial. This loss of significance in the subjects who completed the trial may be explained by persons in the placebo group having a higher burden of illness and associated decreased compliance with the protocol. An important limitation of this study may be the possibility that ibuprofen can mask headache, which is a compulsory criterion for the diagnosis of AMS.

Gertsch JH, Corbett B, Holck PS, Mulcahy A, Watts M, Stillwagon NT, Casto AM, Abramson CH, Vaughan CPA, MacGuire C et al. 2012. Altitude sickness in climbers and efficacy of NSAIDs trial (ASCENT): Randomized, controlled trial of ibuprofen versus placebo for prevention of altitude illness Wilderness and Environmental Medicine, 23 (4), pp. 307-315. | Citations: 24 (Scopus) | Show Abstract | Read more

Objective: To study the effectiveness of ibuprofen versus placebo in preventing acute mountain sickness (AMS) and high altitude headache (HAH). Methods: Double-blind, randomized, placebo-controlled trial. Results: Two hundred ninety-four healthy Western trekkers were recruited on the Everest approach at 4280 m or 4358 m and randomly assigned to receive either 600 mg of ibuprofen or placebo 3 times daily before and during ascent to 4928 m. One hundred eighty-three of 294 participants completed the trial. Of the participants who did not complete the trial, 62 were lost to follow-up and another 49 broke trial protocol. In an intent-to-treat analysis (232 participants), ibuprofen was found to be more effective than placebo in reducing the incidence of AMS (24.4% vs 40.4%; P =.01) and the incidence of HAH (42.3% vs 60.5%; P < .01). Ibuprofen was also superior to placebo in reducing the severity of HAH (4.9% vs 14.7%; P =.01). The end point of oxygen saturation was also higher in the ibuprofen group (80.8 % vs 82.4%; P =.035). For the 183 participants who completed the trial and conformed to the protocol, the incidence of AMS between placebo and treatment groups was not significant (32.9% vs 22.7%; P =.129 for AMS incidence, 9.6% vs 8.2%; P =.74 for AMS severity, 54.8% vs 42.7%; P =.11 for HAH incidence, and 8.2% vs 3.6%; P =.18 for HAH severity). Conclusions: Ibuprofen was found to be effective in preventing AMS in the intent-to-treat analysis group but not in those who completed the trial. This loss of significance in the subjects who completed the trial may be explained by persons in the placebo group having a higher burden of illness and associated decreased compliance with the protocol. An important limitation of this study may be the possibility that ibuprofen can mask headache, which is a compulsory criterion for the diagnosis of AMS. © 2012 Wilderness Medical Society.

Hanaoka M, Droma Y, Basnyat B, Ito M, Kobayashi N, Katsuyama Y, Kubo K, Ota M. 2012. Genetic variants in EPAS1 contribute to adaptation to high-altitude hypoxia in Sherpas. PLoS One, 7 (12), pp. e50566. | Citations: 24 (Scopus) | Show Abstract | Read more

Sherpas comprise a population of Tibetan ancestry in the Himalayan region that is renowned for its mountaineering prowess. The very small amount of available genetic information for Sherpas is insufficient to explain their physiological ability to adapt to high-altitude hypoxia. Recent genetic evidence has indicated that natural selection on the endothelial PAS domain protein 1 (EPAS1) gene was occurred in the Tibetan population during their occupation in the Tibetan Plateau for millennia. Tibetan-specific variations in EPAS1 may regulate the physiological responses to high-altitude hypoxia via a hypoxia-inducible transcription factor pathway. We examined three significant tag single-nucleotide polymorphisms (SNPs, rs13419896, rs4953354, and rs4953388) in the EPAS1 gene in Sherpas, and compared these variants with Tibetan highlanders on the Tibetan Plateau as well as with non-Sherpa lowlanders. We found that Sherpas and Tibetans on the Tibetan Plateau exhibit similar patterns in three EPAS1 significant tag SNPs, but these patterns are the reverse of those in non-Sherpa lowlanders. The three SNPs were in strong linkage in Sherpas, but in weak linkage in non-Sherpas. Importantly, the haplotype structured by the Sherpa-dominant alleles was present in Sherpas but rarely present in non-Sherpas. Surprisingly, the average level of serum erythropoietin in Sherpas at 3440 m was equal to that in non-Sherpas at 1300 m, indicating a resistant response of erythropoietin to high-altitude hypoxia in Sherpas. These observations strongly suggest that EPAS1 is under selection for adaptation to the high-altitude life of Tibetan populations, including Sherpas. Understanding of the mechanism of hypoxia tolerance in Tibetans is expected to provide lights to the therapeutic solutions of some hypoxia-related human diseases, such as cardiovascular disease and cancer.

Küpper T, Milledge JS, Hillebrandt D, Kubalová J, Hefti U, Basnyat B, Gieseler U, Pullan R, Schöffl V. 2011. Work in hypoxic conditions--consensus statement of the Medical Commission of the Union Internationale des Associations d'Alpinisme (UIAA MedCom). Ann Occup Hyg, 55 (4), pp. 369-386. | Citations: 15 (Scopus) | Show Abstract | Read more

OBJECTIVES: The Commission gives recommendations on how to provide health and safety for employees in different kinds of low oxygen atmospheres. So far, no recommendations exist that take into account the several factors we have outlined in this report. METHODS: The health and safety recommendations of several countries were analysed for their strength and deficiencies. The scientific literature was checked (Medline, etc.) and evaluated for relevance of the topic. Typical situations of work in hypoxia were defined and their specific risks described. Specific recommendations are provided for any of these situations. RESULTS: We defined four main groups with some subgroups (main risk in brackets): short exposure (pressure change), limited exposure (acute altitude disease), expatriates (chronic altitude disease), and high-altitude populations (re-entry pulmonary oedema). For healthy unacclimatized persons, an acute but limited exposure down to 13% O(2) does not cause a health risk. Employees should be advised to leave hypoxic areas for any break, if possible. Detailed advice is given for any other situation and pre-existing diseases. CONCLUSIONS: If the specific risk of the respective type of hypoxia is taken into account, a pragmatic approach to provide health and safety for employees is possible. In contrast to other occupational exposures, a repeated exposure as often as possible is of benefit as it causes partial acclimatization. The consensus statement was approved by written consent in lieu of a meeting in July 2009.

Arjyal A, Basnyat B, Koirala S, Karkey A, Dongol S, Agrawaal KK, Shakya N, Shrestha K, Sharma M, Lama S et al. 2011. Gatifloxacin versus chloramphenicol for uncomplicated enteric fever: an open-label, randomised, controlled trial. Lancet Infect Dis, 11 (6), pp. 445-454. | Citations: 34 (Scopus) | Show Abstract | Read more

BACKGROUND: We aimed to investigate whether gatifloxacin, a new generation and affordable fluoroquinolone, is better than chloramphenicol for the treatment of uncomplicated enteric fever in children and adults. METHODS: We did an open-label randomised superiority trial at Patan Hospital, Kathmandu, Nepal, to investigate whether gatifloxacin is more effective than chloramphenicol for treating uncomplicated enteric fever. Children and adults clinically diagnosed with enteric fever received either gatifloxacin (10 mg/kg) once a day for 7 days, or chloramphenicol (75 mg/kg per day) in four divided doses for 14 days. Patients were randomly allocated treatment (1:1) in blocks of 50, without stratification. Allocations were placed in sealed envelopes opened by the study physician once a patient was enrolled into the trial. Masking was not possible because of the different formulations and ways of giving the two drugs. The primary outcome measure was treatment failure, which consisted of at least one of the following: persistent fever at day 10, need for rescue treatment, microbiological failure, relapse until day 31, and enteric-fever-related complications. The primary outcome was assessed in all patients randomly allocated treatment and reported separately for culture-positive patients and for all patients. Secondary outcome measures were fever clearance time, late relapse, and faecal carriage. The trial is registered on controlled-trials.com, number ISRCTN 53258327. FINDINGS: 844 patients with a median age of 16 (IQR 9-22) years were enrolled in the trial and randomly allocated a treatment. 352 patients had blood-culture-confirmed enteric fever: 175 were treated with chloramphenicol and 177 with gatifloxacin. 14 patients had treatment failure in the chloramphenicol group, compared with 12 in the gatifloxacin group (hazard ratio [HR] of time to failure 0·86, 95% CI 0·40-1·86, p=0·70). The median time to fever clearance was 3·95 days (95% CI 3·68-4·68) in the chloramphenicol group and 3·90 days (3·58-4·27) in the gatifloxacin group (HR 1·06, 0·86-1·32, p=0·59). At 1 month only, three of 148 patients were stool-culture positive in the chloramphenicol group and none in the gatifloxacin group. At the end of 3 months only one person had a positive stool culture in the chloramphenicol group. There were no other positive stool cultures even at the end of 6 months. Late relapses were noted in three of 175 patients in the culture-confirmed chloramphenicol group and two of 177 in the gatifloxacin group. There were no culture-positive relapses after day 62. 99 patients (24%) experienced 168 adverse events in the chloramphenicol group and 59 (14%) experienced 73 events in the gatifloxacin group. INTERPRETATION: Although no more efficacious than chloramphenicol, gatifloxacin should be the preferred treatment for enteric fever in developing countries because of its shorter treatment duration and fewer adverse events. FUNDING: Wellcome Trust.

Basnyat B. 2011. Malaria-attributed death rates in India. Lancet, 377 (9770), pp. 993. | Citations: 3 (Web of Science Lite) | Read more

Jansen GFA, Basnyat B. 2011. Brain blood flow in Andean and Himalayan high-altitude populations: evidence of different traits for the same environmental constraint. J Cereb Blood Flow Metab, 31 (2), pp. 706-714. | Citations: 13 (Scopus) | Show Abstract | Read more

Humans have populated the Tibetan plateau much longer than the Andean Altiplano. It is thought that the difference in length of occupation of these altitudes has led to different responses to the stress of hypoxia. As such, Andean populations have higher hematocrit levels than Himalayans. In contrast, Himalayans have increased circulation to certain organ systems to meet tissue oxygen demand. In this study, we hypothesize that cerebral blood flow (CBF) is higher in Himalayans than in Andeans. Using a MEDLINE and EMBASE search, we included 10 studies that investigated CBF in Andeans and Himalayans between 3,658 and 4,330 m altitude. The CBF values were corrected for differences in hematocrit and arterial oxygen saturation. The data of these studies show a mean hematocrit of 50% in Himalayans and 54.1% in Andeans. Arterial oxygen saturation was 86.9% in Andeans and 88.4% in Himalayans. The CBF in Himalayans was slightly elevated compared with sea-level subjects, and was 24% higher compared with Andeans. After correction for hematorit and arterial oxygen saturation, CBF was ∼20% higher in Himalayans compared with Andeans. Altered brain metabolism in Andeans, and/or increased nitric oxide availability in Himalayans may have a role to explain this difference in brain blood flow.

Basnyat B, Holck PS, Pun M, Halverson S, Szawarski P, Gertsch J, Steif M, Powell S, Khanal S, Joshi A et al. 2011. Spironolactone does not prevent acute mountain sickness: a prospective, double-blind, randomized, placebo-controlled trial by SPACE Trial Group (spironolactone and acetazolamide trial in the prevention of acute mountain sickness group). Wilderness Environ Med, 22 (1), pp. 15-22. | Citations: 22 (Scopus) | Show Abstract | Read more

OBJECTIVES: Over the last 20 years a number of small trials have reported that spironolactone effectively prevents acute mountain sickness (AMS), but to date there have been no large randomized trials investigating the efficacy of spironolactone in prevention of AMS. Hence, a prospective, double-blind, randomized, placebo-controlled trial was conducted to evaluate the efficacy of spironolactone in the prevention of AMS. METHODS: Participants were sampled from a diverse population of western trekkers recruited at 4300 m on the Mount Everest base camp approach (Nepal side) en route to the study endpoint at 5000 m. Three hundred and eleven healthy trekkers were enrolled, and 251 completed the trial from October to November 2007. Participants were randomly assigned to receive at least 3 doses of spironolactone 50 mg BID, acetazolamide 250 mg BID, or visually matched placebo. A Lake Louise AMS Score of 3 or more, together with the presence of headache and 1 other symptom, was used to evaluate the incidence and severity of AMS. Secondary outcome measures were blood oxygen content and the incidence and severity of high altitude headache (HAH). RESULTS: Acetazolamide was more effective than spironolactone in preventing AMS (OR = 0.28, 95% CI 0.12-0.60, p < 0.01). Spironolactone was not significantly different from placebo in the prevention of AMS. AMS incidence for placebo was 20.3%, acetazolamide 10.5%, and spironolactone 29.4%. Oxygen saturation was also significantly increased in the acetazolamide group (83% ± 0.04) vs spironolactone group (80% ± 0.05, p < 0.01). CONCLUSIONS: Spironolactone (50 mg BID) was ineffective in comparison to acetazolamide (250 mg BID) in the prevention of AMS in partially acclimatized western trekkers ascending to 5000 m in the Nepali Himalaya.

Baker S, Holt KE, Clements ACA, Karkey A, Arjyal A, Boni MF, Dongol S, Hammond N, Koirala S, Duy PT et al. 2011. Combined high-resolution genotyping and geospatial analysis reveals modes of endemic urban typhoid fever transmission. Open Biol, 1 (2), pp. 110008. | Citations: 43 (Scopus) | Show Abstract | Read more

Typhoid is a systemic infection caused by Salmonella Typhi and Salmonella Paratyphi A, human-restricted bacteria that are transmitted faeco-orally. Salmonella Typhi and S. Paratyphi A are clonal, and their limited genetic diversity has precluded the identification of long-term transmission networks in areas with a high disease burden. To improve our understanding of typhoid transmission we have taken a novel approach, performing a longitudinal spatial case-control study for typhoid in Nepal, combining single-nucleotide polymorphism genotyping and case localization via global positioning. We show extensive clustering of typhoid occurring independent of population size and density. For the first time, we demonstrate an extensive range of genotypes existing within typhoid clusters, and even within individual households, including some resulting from clonal expansion. Furthermore, although the data provide evidence for direct human-to-human transmission, we demonstrate an overwhelming contribution of indirect transmission, potentially via contaminated water. Consistent with this, we detected S. Typhi and S. Paratyphi A in water supplies and found that typhoid was spatially associated with public water sources and low elevation. These findings have implications for typhoid-control strategies, and our innovative approach may be applied to other diseases caused by other monophyletic or emerging pathogens.

Subedi BH, Pokharel J, Goodman TL, Amatya S, Freer L, Banskota N, Johnson E, Basnyat B. 2010. Complications of steroid use on Mt. Everest. Wilderness Environ Med, 21 (4), pp. 345-348. | Citations: 20 (Web of Science Lite) | Show Abstract | Read more

Steroids are used for the prevention and treatment of high-altitude illnesses. However, these agents can cause significant side effects. We report a case of altered mental status, gastrointestinal bleeding, skin rash, and avascular necrosis in a climber taking prophylactic dexamethasone prior to an attempt to climb Mt Everest. High-altitude cerebral edema (HACE), steroid toxicity, and acute adrenal crisis can have similar clinical presentations. Differentiating between these life-threatening conditions at high altitude is essential for successful treatment.

Parry CM, Thuy CT, Dongol S, Karkey A, Vinh H, Chinh NT, Duy PT, Thieu Nga TV, Campbell JI, Van Minh Hoang N et al. 2010. Suitable disk antimicrobial susceptibility breakpoints defining Salmonella enterica serovar Typhi isolates with reduced susceptibility to fluoroquinolones. Antimicrob Agents Chemother, 54 (12), pp. 5201-5208. | Citations: 33 (Scopus) | Show Abstract | Read more

Infections with Salmonella enterica serovar Typhi isolates that have reduced susceptibility to ofloxacin (MIC ≥ 0.25 μg/ml) or ciprofloxacin (MIC ≥ 0.125 μg/ml) have been associated with a delayed response or clinical failure following treatment with these antimicrobials. These isolates are not detected as resistant using current disk susceptibility breakpoints. We examined 816 isolates of S. Typhi from seven Asian countries. Screening for nalidixic acid resistance (MIC ≥ 16 μg/ml) identified isolates with an ofloxacin MIC of ≥0.25 μg/ml with a sensitivity of 97.3% (253/260) and specificity of 99.3% (552/556). For isolates with a ciprofloxacin MIC of ≥0.125 μg/ml, the sensitivity was 92.9% (248/267) and specificity was 98.4% (540/549). A zone of inhibition of ≤28 mm around a 5-μg ofloxacin disc detected strains with an ofloxacin MIC of ≥0.25 μg/ml with a sensitivity of 94.6% (246/260) and specificity of 94.2% (524/556). A zone of inhibition of ≤30 mm detected isolates with a ciprofloxacin MIC of ≥0.125 μg/ml with a sensitivity of 94.0% (251/267) and specificity of 94.2% (517/549). An ofloxacin MIC of ≥0.25 μg/ml and a ciprofloxacin MIC of ≥0.125 μg/ml detected 74.5% (341/460) of isolates with an identified quinolone resistance-inducing mutation and 81.5% (331/406) of the most common mutant (carrying a serine-to-phenylalanine mutation at codon 83 in the gyrA gene). Screening for nalidixic acid resistance or ciprofloxacin and ofloxacin disk inhibition zone are suitable for detecting S. Typhi isolates with reduced fluoroquinolone susceptibility.

Basnyat B. 2010. Neglected hepatitis E and typhoid vaccines. Lancet, 376 (9744), pp. 869. | Citations: 3 (Web of Science Lite) | Read more

Gertsch JH, Lipman GS, Holck PS, Merritt A, Mulcahy A, Fisher RS, Basnyat B, Allison E, Hanzelka K, Hazan A et al. 2010. Prospective, double-blind, randomized, placebo-controlled comparison of acetazolamide versus ibuprofen for prophylaxis against high altitude headache: the Headache Evaluation at Altitude Trial (HEAT). Wilderness Environ Med, 21 (3), pp. 236-243. | Citations: 46 (Scopus) | Show Abstract | Read more

OBJECTIVE: High altitude headache (HAH) is the most common neurological complaint at altitude and the defining component of acute mountain sickness (AMS). However, there is a paucity of literature concerning its prevention. Toward this end, we initiated a prospective, double-blind, randomized, placebo-controlled trial in the Nepal Himalaya designed to compare the effectiveness of ibuprofen and acetazolamide for the prevention of HAH. METHODS: Three hundred forty-three healthy western trekkers were recruited at altitudes of 4280 m and 4358 m and assigned to receive ibuprofen 600 mg, acetazolamide 85 mg, or placebo 3 times daily before continued ascent to 4928 m. Outcome measures included headache incidence and severity, AMS incidence and severity on the Lake Louise AMS Questionnaire (LLQ), and visual analog scale (VAS). RESULTS: Two hundred sixty-five of 343 subjects completed the trial. HAH incidence was similar when treated with acetazolamide (27.1%) or ibuprofen (27.5%; P = .95), and both agents were significantly more effective than placebo (45.3%; P = .01). AMS incidence was similar when treated with acetazolamide (18.8%) or ibuprofen (13.7%; P = .34), and both agents were significantly more effective than placebo (28.6%; P = .03). In fully compliant participants, moderate or severe headache incidence was similar when treated with acetazolamide (3.8%) or ibuprofen (4.7%; P = .79), and both agents were significantly more effective than placebo (13.5%; P = .03). CONCLUSIONS: Ibuprofen and acetazolamide were similarly effective in preventing HAH. Ibuprofen was similar to acetazolamide in preventing symptoms of AMS, an interesting finding that implies a potentially new approach to prevention of cerebral forms of acute altitude illness.

Subedi BH, Pokharel J, Thapa R, Banskota N, Basnyat B. 2010. Frostbite in a Sherpa. Wilderness Environ Med, 21 (2), pp. 127-129. | Citations: 3 (Scopus) | Show Abstract | Read more

Frostbite is frequently seen in high altitude climbers. Many Sherpas, members of an ethnic community living high in the Himalayas in Nepal, help the climbers as a guide or an assistant. They often seem to undertake few precautionary measures thus suffer more from frostbite. A young Sherpa, who had reached the top of Mt Kanchenjunga in March 2009, suffered from deep frostbite in his fingers. Fortunately, he recovered well with generous treatment. Though there is no evidence whether Sherpas are more or less prone to frostbite, simple techniques for adequate prevention of hypoxia, hypothermia and dehydration will benefit any climber to the high altitudes.

Holt KE, Baker S, Dongol S, Basnyat B, Adhikari N, Thorson S, Pulickal AS, Song Y, Parkhill J, Farrar JJ et al. 2010. High-throughput bacterial SNP typing identifies distinct clusters of Salmonella Typhi causing typhoid in Nepalese children. BMC Infect Dis, 10 (1), pp. 144. | Citations: 46 (Scopus) | Show Abstract | Read more

BACKGROUND: Salmonella Typhi (S. Typhi) causes typhoid fever, which remains an important public health issue in many developing countries. Kathmandu, the capital of Nepal, is an area of high incidence and the pediatric population appears to be at high risk of exposure and infection. METHODS: We recently defined the population structure of S. Typhi, using new sequencing technologies to identify nearly 2,000 single nucleotide polymorphisms (SNPs) that can be used as unequivocal phylogenetic markers. Here we have used the GoldenGate (Illumina) platform to simultaneously type 1,500 of these SNPs in 62 S. Typhi isolates causing severe typhoid in children admitted to Patan Hospital in Kathmandu. RESULTS: Eight distinct S. Typhi haplotypes were identified during the 20-month study period, with 68% of isolates belonging to a subclone of the previously defined H58 S. Typhi. This subclone was closely associated with resistance to nalidixic acid, with all isolates from this group demonstrating a resistant phenotype and harbouring the same resistance-associated SNP in GyrA (Phe83). A secondary clone, comprising 19% of isolates, was observed only during the second half of the study. CONCLUSIONS: Our data demonstrate the utility of SNP typing for monitoring bacterial populations over a defined period in a single endemic setting. We provide evidence for genotype introduction and define a nalidixic acid resistant subclone of S. Typhi, which appears to be the dominant cause of severe pediatric typhoid in Kathmandu during the study period.

Thapa R, Banskota N, Pokharel J, Subedi BH, Basnyat B. 2010. Another typhoid patient from Japan. J Travel Med, 17 (3), pp. 199-200. | Citations: 2 (Web of Science Lite) | Show Abstract | Read more

Typhoid treatment was empirically started in a Japanese patient with undifferentiated fever in Nepal since Japanese tourists, unlike most Americans and Europeans to South Asia, are unable to obtain typhoid vaccination in Japan even for travel to this area of high endemicity. Subsequently, his blood culture grew out Salmonella typhi.

Basnyat B. 2010. Typhoid fever in the United States and antibiotic choice. JAMA, 303 (1), pp. 34. | Citations: 4 (Scopus) | Read more

Nga TVT, Karkey A, Dongol S, Thuy HN, Dunstan S, Holt K, Tu LTP, Campbell JI, Chau TT, Chau NVV et al. 2010. The sensitivity of real-time PCR amplification targeting invasive Salmonella serovars in biological specimens. BMC Infect Dis, 10 (1), pp. 125. | Citations: 43 (Scopus) | Show Abstract | Read more

BACKGROUND: PCR amplification for the detection of pathogens in biological material is generally considered a rapid and informative diagnostic technique. Invasive Salmonella serovars, which cause enteric fever, can be commonly cultured from the blood of infected patients. Yet, the isolation of invasive Salmonella serovars from blood is protracted and potentially insensitive. METHODS: We developed and optimised a novel multiplex three colour real-time PCR assay to detect specific target sequences in the genomes of Salmonella serovars Typhi and Paratyphi A. We performed the assay on DNA extracted from blood and bone marrow samples from culture positive and negative enteric fever patients. RESULTS: The assay was validated and demonstrated a high level of specificity and reproducibility under experimental conditions. All bone marrow samples tested positive for Salmonella, however, the sensitivity on blood samples was limited. The assay demonstrated an overall specificity of 100% (75/75) and sensitivity of 53.9% (69/128) on all biological samples. We then tested the PCR detection limit by performing bacterial counts after inoculation into blood culture bottles. CONCLUSIONS: Our findings corroborate previous clinical findings, whereby the bacterial load of S. Typhi in peripheral blood is low, often below detection by culture and, consequently, below detection by PCR. Whilst the assay may be utilised for environmental sampling or on differing biological samples, our data suggest that PCR performed directly on blood samples may be an unsuitable methodology and a potentially unachievable target for the routine diagnosis of enteric fever.

Karkey A, Arjyal A, Anders KL, Boni MF, Dongol S, Koirala S, My PVT, Nga TVT, Clements ACA, Holt KE et al. 2010. The burden and characteristics of enteric fever at a healthcare facility in a densely populated area of Kathmandu. PLoS One, 5 (11), pp. e13988. | Citations: 28 (Scopus) | Show Abstract | Read more

Enteric fever, caused by Salmonella enterica serovars Typhi and Paratyphi A (S. Typhi and S. Paratyphi A) remains a major public health problem in many settings. The disease is limited to locations with poor sanitation which facilitates the transmission of the infecting organisms. Efficacious and inexpensive vaccines are available for S. Typhi, yet are not commonly deployed to control the disease. Lack of vaccination is due partly to uncertainty of the disease burden arising from a paucity of epidemiological information in key locations. We have collected and analyzed data from 3,898 cases of blood culture-confirmed enteric fever from Patan Hospital in Lalitpur Sub-Metropolitan City (LSMC), between June 2005 and May 2009. Demographic data was available for a subset of these patients (n = 527) that were resident in LSMC and who were enrolled in trials. We show a considerable burden of enteric fever caused by S. Typhi (2,672; 68.5%) and S. Paratyphi A (1,226; 31.5%) at this Hospital over a four year period, which correlate with seasonal fluctuations in rainfall. We found that local population density was not related to incidence and we identified a focus of infections in the east of LSMC. With data from patients resident in LSMC we found that the median age of those with S. Typhi (16 years) was significantly less than S. Paratyphi A (20 years) and that males aged 15 to 25 were disproportionately infected. Our findings provide a snapshot into the epidemiological patterns of enteric fever in Kathmandu. The uneven distribution of enteric fever patients within the population suggests local variation in risk factors, such as contaminated drinking water. These findings are important for initiating a vaccination scheme and improvements in sanitation. We suggest any such intervention should be implemented throughout the LSMC area.

Total publications on this page: 130

Total citations for publications on this page: 1069