Dr Audrey Dubot-Peres

Research Area: Microbiology
Scientific Themes: Immunology & Infectious Disease and Tropical Medicine & Global Health

The program “Viral infections of medical importance in Laos” is conducted in collaboration with the unit: UMR "Unité des Virus Emergents" (UVE: Aix-Marseille Univ – IRD 190 – Inserm 1207 – IHU Méditerranée Infection), Marseille, France.

Viral infections (Japanese encephalitis, dengue, acute respiration infection, gastro-enteritis, hand foot and mouth disease…) represent a major public health burden in Laos and important challenge for patient management. Medical issues are combined with diagnostic difficulties and lack in epidemiological data. The main focus of this program is to develop research by structuring our activities around the implementation of research projects on emerging viral disease and building capacity at the Microbiology Laboratory at Mahosot Hospital, Vientiane, Laos.

Research topics:

Central nervous system (CNS) infections:

  • Causes of CNS infections in patient admitted to Mahosot Hospital, aetiologies, epidemiology and treatment.
  • Adaptation of techniques for CSF transportation and diagnosis from remote areas.
  • Molecular epidemiology of Enteroviruses circulating in Laos.

Dengue and arboviruses:

  • Undifferentiated fever, aetiologies and their epidemiology.
  • Molecular epidemiology of Dengue virus circulating in Laos.
  • Development of tools for sample collection from remote rural areas for subsequent molecular analysis.

Acute respiratory infections:

  • Acute respiratory infections in children admitted to Mahosot hospital, aetiologies, epidemiology and risk factors.
  • Importance of Respiratory Syncytial Virus infections in young children admitted with pneumonia.

There are no collaborations listed for this principal investigator.

Castonguay-Vanier J, Klitting R, Sengvilaipaseuth O, Piorkowski G, Baronti C, Sibounheuang B, Vongsouvath M, Chanthongthip A, Thongpaseuth S, Mayxay M et al. 2018. Molecular epidemiology of dengue viruses in three provinces of Lao PDR, 2006-2010. PLoS Negl Trop Dis, 12 (1), pp. e0006203. | Show Abstract | Read more

Few data on dengue epidemiology are available for Lao PDR. Here, we provide information on the complexity of dengue epidemiology in the country, demonstrating dynamic circulation that varies over space and time, according to serotype. We recruited 1,912 consenting patients presenting with WHO dengue criteria at Mahosot Hospital, Vientiane (central Laos), between 2006 and 2010. Between 2008 and 2010, 1,413 patients with undifferentiated fever were also recruited at Luang Namtha (LNT) Provincial Hospital (northern Laos) and 555 at Salavan (SV) Provincial Hospital (southern Laos). We report significant variations in Dengue virus (DENV) circulation between the three sites. Peaks of DENV infection were observed in the rainy seasons, although 11% of confirmed cases in the provinces and 4.6% in the capital were detected during the dry and cool seasons (between December and February). Four DENV serotypes were detected among the 867 RT-PCR positive patients: 76.9% DENV-1, 9.6% DENV-2, 7.7% DENV-4 and 5.3% DENV-3. DENV-1 was the predominant serotype throughout the study except in LNT in 2008 and 2009 when it was DENV-2. Before July 2009, DENV-2 was not detected in SV and only rarely detected in Vientiane. DENV-3 and DENV-4 were commonly detected in Vientiane, before 2008 for DENV-4 and after 2009 for DENV-3. The phylogenetic analyses of DENV envelope sequences suggest concurrent multiple introductions of new strains as well as active DENV circulation throughout Laos and with neighboring countries. It is therefore of great importance to develop and strengthen a year-round nation-wide surveillance network in order to collect data that would allow anticipation of public health issues caused by the occurrence of large dengue outbreaks.

Sengvilaipaseuth O, Castonguay-Vanier J, Chanthongthip A, Phonemixay O, Thongpaseuth S, Vongsouvath M, Newton PN, Bharucha T, Dubot-Pérès A. 2017. Poor performance of two rapid immunochromatographic assays for anti-Japanese encephalitis virus immunoglobulin M detection in cerebrospinal fluid and serum from patients with suspected Japanese encephalitis virus infection in Laos. Trans R Soc Trop Med Hyg, 111 (8), pp. 373-377. | Show Abstract | Read more

Background: Japanese encephalitis virus (JEV) is a leading identified cause of encephalitis in Asia, often occurring in rural areas with poor access to laboratory diagnostics. We evaluated two rapid diagnostic tests (RDTs) for anti-JEV immunoglobulin M (IgM) detection. Methods: Consecutive cerebrospinal fluid and serum from 388 patients (704 samples) with suspected JEV infections admitted to six hospitals in Laos were tested with one of two SD-Bioline anti-JEV IgM RDTs and the World Health Organization standard anti-JEV IgM enzyme-linked immunosorbent assay (ELISA; Panbio Japanese Encephalitis-Dengue IgM Combo ELISA. Results and Conclusions: The performance of both RDTs showed strikingly low sensitivity in comparison to anti-JEV IgM antibody capture ELISA (2.1-51.4%), suggesting low sensitivity of the RDTs. We highlight the fundamental prerequisite to validate RDTs prior to use to ensure that they meet standards for testing.

Ming DKY, Rattanavong S, Bharucha T, Sengvilaipaseuth O, Dubot-Pérès A, Newton PN, Robinson MT. 2017. Angiostrongylus cantonensis DNA in Cerebrospinal Fluid of Persons with Eosinophilic Meningitis, Laos. Emerg Infect Dis, 23 (12), pp. 2112-2113. | Show Abstract | Read more

Definitive identification of Angiostrongylus cantonensis parasites from clinical specimens is difficult. As a result, regional epidemiology and burden are poorly characterized. To ascertain presence of this parasite in patients in Laos with eosinophilic meningitis, we performed quantitative PCRs on 36 cerebrospinal fluid samples; 4 positive samples confirmed the parasite's presence.

Nguyen VH, Dubot-Pérès A, Russell FM, Dance DAB, Vilivong K, Phommachan S, Syladeth C, Lai J, Lim R, Morpeth M et al. 2017. Acute respiratory infections in hospitalized children in Vientiane, Lao PDR - the importance of Respiratory Syncytial Virus. Sci Rep, 7 (1), pp. 9318. | Show Abstract | Read more

The Human respiratory syncytial virus (RSV) is one of the most important viral pathogens, causing epidemics of acute respiratory infection (ARI), especially bronchiolitis and pneumonia, in children worldwide. To investigate the RSV burden in Laos, we conducted a one-year study in children <5 years old admitted to Mahosot Hospital, Vientiane Capital, to describe clinical and epidemiological characteristics and predictive factors for severity of RSV-associated ARI. Pooled nasal and throat swabs were tested using multiplex real-time PCR for 33 respiratory pathogens (FTD® kit). A total of 383 patients were included, 277 (72.3%) of whom presented with pneumonia. 377 (98.4%) patients were positive for at least one microorganism, of which RSV was the most common virus (41.0%), with a peak observed between June and September, corresponding to the rainy season. Most RSV inpatients had pneumonia (84.1%), of whom 35% had severe pneumonia. Children <3-months old were a high-risk group for severe pneumonia, independently of RSV infection. Our study suggests that RSV infection is frequent in Laos and commonly associated with pneumonia in hospitalized young children. Further investigations are required to provide a better overall view of the Lao nationwide epidemiology and public health burden of RSV infection over time.

Sengvilaipaseuth O, Phommasone K, de Lamballerie X, Vongsouvath M, Phonemixay O, Blacksell SD, Mayxay M, Keomany S, Souvannasing P, Newton PN, Dubot-Pérès A. 2017. Temperature of a Dengue Rapid Diagnostic Test under Tropical Climatic Conditions: A Follow Up Study. PLoS One, 12 (1), pp. e0170359. | Show Abstract | Read more

The Dengue Duo Rapid Diagnostic Test (SD Dengue RDT) has good specificity and sensitivity for dengue diagnosis in rural tropical areas. In a previous study, using four control sera, we demonstrated that that the diagnostic accuracy of these RDTs remains stable after long-term storage at high temperatures. We extended this study by testing sera from 119 febrile patients collected between July-November 2012 at Salavan Provincial Hospital (southern Laos) with RDTs stored for 6 months at 4°C, 35° and in a hut (miniature traditional house) at Lao ambient temperatures. The dengue NS1 antigen results from RDTs stored at 35°C and in the hut demonstrated 100% agreement with those stored at 4°C. However, lower positive percent agreements, with broad 95%CI, were observed for the tests: IgM, 60% (14.7-94.7) and 40% (5.3-85.3) for RDTs store at 35°C and in the hut, compared to those stored at 4°C, respectively. This study strenghtens the evidence of the robustness of the NS1 antigen detection RDT for the diagnosis of dengue after storage at tropical temperatures.

Vongsouvath M, Phommasone K, Sengvilaipaseuth O, Kosoltanapiwat N, Chantratita N, Blacksell SD, Lee SJ, de Lamballerie X, Mayxay M, Keomany S et al. 2016. Using Rapid Diagnostic Tests as a Source of Viral RNA for Dengue Serotyping by RT-PCR - A Novel Epidemiological Tool. PLoS Negl Trop Dis, 10 (5), pp. e0004704. | Show Abstract | Read more

BACKGROUND: Dengue virus infection causes major public health problems in tropical and subtropical areas. In many endemic areas, including the Lao PDR, inadequate access to laboratory facilities is a major obstacle to surveillance and study of dengue epidemiology. Filter paper is widely used for blood collection for subsequent laboratory testing for antibody and nucleic acid detection. For the first time, we demonstrate that dengue viral RNA can be extracted from dengue rapid diagnostic tests (RDT) and then submitted to real-time RT-PCR for serotyping. METHODOLOGY/PRINCIPAL FINDINGS: We evaluated the Standard Diagnostics (SD) Bioline Dengue Duo RDT, a commonly used test in dengue endemic areas. First, using the QIAamp RNA kit, dengue RNA was purified from the sample pad of the NS1 RDT loaded with virus isolates of the four serotypes, then quantified by RT-PCR. We observed greater recovery of virus, with a mean of 27 times more RNA recovered from RDT, than from filter paper. Second, we evaluated dengue NS1 RDTs from patients at Mahosot Hospital, Vientiane, (99 patients) and from rural Salavan Provincial Hospital (362 patients). There was good agreement between dengue RT-PCR from NS1 RDT with RT-PCR performed on RNA extracted from patient sera, either using RDT loaded with blood (82.8% and 91.4%, in Vientiane and Salavan, respectively) or serum (91.9% and 93.9%). There was 100% concordance between RDT and serum RT-PCR of infecting dengue serotype. CONCLUSIONS/SIGNIFICANCE: Therefore, the collection of NS1 positive RDTs, which do not require cold storage, may be a novel approach for dengue serotyping by RT-PCR and offers promising prospects for the collection of epidemiological data from previously inaccessible tropical areas to aid surveillance and public health interventions.

Chansamouth V, Thammasack S, Phetsouvanh R, Keoluangkot V, Moore CE, Blacksell SD, Castonguay-Vanier J, Dubot-Pérès A, Tangkhabuanbutra J, Tongyoo N et al. 2016. The Aetiologies and Impact of Fever in Pregnant Inpatients in Vientiane, Laos. PLoS Negl Trop Dis, 10 (4), pp. e0004577. | Show Abstract | Read more

INTRODUCTION: Laos has the highest maternal mortality ratio in mainland Southeast Asia and a high incidence of infectious diseases. Globally, malaria has been the pathogen most intensively investigated in relation to impact on pregnancy, but there has been relatively little research on the aetiology and impact of other diseases. We therefore aimed to determine the causes and impact of fever in pregnant women admitted to two central hospitals in Vientiane City, Lao PDR (Laos). MATERIALS AND METHODS: This hospital-based prospective study was conducted in Mahosot Hospital and the Mother and Child Hospital, Vientiane, between 2006 and 2010, with the aim to recruit 250 consenting pregnant women admitted with tympanic temperature ≥37.5°C. Primary outcome was the cause of fever and secondary outcomes were pregnancy outcomes. Specific investigations (culture, antigen, molecular and serological tests) were performed to investigate causes of fever. After discharge, all pregnant women were asked to return for review and convalescence serum on day 10-14 and were monitored until delivery. PRINCIPLE FINDINGS: 250 pregnant women were recruited to this study between February 2006 and November 2010. Fifty percent were pregnant for the first time. Their median (range) gestational age on admission was 24 (4-43) weeks. The median (range) tympanic admission temperature was 38.5°C (37.5-40.5°C). Fifteen percent of patients stated that they had taken antibiotics before admission. Headache, myalgia, back pain and arthralgia were described by >60% of patients and 149 (60%) were given a laboratory diagnosis. Of those with confirmed diagnoses, 132 (53%) had a single disease and 17 (7%) had apparent mixed diseases. Among those who had a single disease, dengue fever was the most common diagnosis, followed by pyelonephritis, scrub typhus, murine typhus and typhoid. Patients were also diagnosed with tuberculosis, appendicitis, Staphylococcus aureus septicemia, leptospirosis, Japanese encephalitis virus infection and Plasmodium falciparum malaria. Severe consequences, including maternal death, miscarriage, stillbirth, low birth weight and preterm birth, were found among 28 (78%) mothers with dengue fever, rickettsioses and typhoid. CONCLUSION: Fevers other than malaria, such as dengue, pyelonephritis, rickettsioses and typhoid are common causes of fever during pregnancy in the Asian tropics. Further investigations of their impact in the community on maternal death, fetal loss, vertical transmission, low birth weight and preterm birth are needed.

Bharucha T, Sengvilaipaseuth O, Chanthongthip A, Phuangpanom E, Phonemixay O, Vongsouvath M, Lee S, Newton P, Dubot-Peres A. 2016. Dried cerebrospinal fluid spots for diagnosing Japanese Encephalitis Virus (JEV) infection by Anti-JEV IgM antibody capture enzyme-linked immunosorbent assay: Harnessing the potential of a fully saturated pre-cut filter paper disc INTERNATIONAL JOURNAL OF INFECTIOUS DISEASES, 45 pp. 151-151. | Read more

Bharucha T, Chanthongthip A, Phuangpanom S, Phonemixay O, Sengvilaipaseuth O, Vongsouvath M, Lee S, Newton PN, Dubot-Peres A. 2016. Pre-cut Filter Paper for Detecting Anti-Japanese Encephalitis Virus IgM from Dried Cerebrospinal Fluid Spots PLOS NEGLECTED TROPICAL DISEASES, 10 (3), | Read more

Bharucha T, Chanthongthip A, Phuangpanom S, Phonemixay O, Sengvilaipaseuth O, Vongsouvath M, Lee S, Newton PN, Dubot-Pérès A. 2016. Pre-cut Filter Paper for Detecting Anti-Japanese Encephalitis Virus IgM from Dried Cerebrospinal Fluid Spots. PLoS Negl Trop Dis, 10 (3), pp. e0004516. | Show Abstract | Read more

BACKGROUND: The use of filter paper as a simple, inexpensive tool for storage and transportation of blood, 'Dried Blood Spots' or Guthrie cards, for diagnostic assays is well-established. In contrast, there are a paucity of diagnostic evaluations of dried cerebrospinal fluid (CSF) spots. These have potential applications in low-resource settings, such as Laos, where laboratory facilities for central nervous system (CNS) diagnostics are only available in Vientiane. In Laos, a major cause of CNS infection is Japanese encephalitis virus (JEV). We aimed to develop a dried CSF spot protocol and to evaluate its diagnostic performance using the World Health Organisation recommended anti-JEV IgM antibody capture enzyme-linked immunosorbent assay (JEV MAC-ELISA). METHODOLOGY AND PRINCIPAL FINDINGS: Sample volumes, spotting techniques and filter paper type were evaluated using a CSF-substitute of anti-JEV IgM positive serum diluted in Phosphate Buffer Solution (PBS) to end-limits of detection by JEV MAC-ELISA. A conventional protocol, involving eluting one paper punch in 200 μl PBS, did not detect the end-dilution, nor did multiple punches utilising diverse spotting techniques. However, pre-cut filter paper enabled saturation with five times the volume of CSF-substitute, sufficiently improving sensitivity to detect the end-dilution. The diagnostic accuracy of this optimised protocol was compared with routine, neat CSF in a pilot, retrospective study of JEV MAC-ELISA on consecutive CSF samples, collected 2009-15, from three Lao hospitals. In comparison to neat CSF, 132 CSF samples stored as dried CSF spots for one month at 25-30 °C showed 81.6% (65.7-92.3 95%CI) positive agreement, 96.8% (91.0-99.3 95%CI) negative agreement, with a kappa coefficient of 0.81 (0.70-0.92 95%CI). CONCLUSIONS/SIGNIFICANCE: The novel design of pre-cut filter paper saturated with CSF could provide a useful tool for JEV diagnostics in settings with limited laboratory access. It has the potential to improve national JEV surveillance and inform vaccination policies. The saturation of filter paper has potential use in the wider context of pathogen detection, including dried spots for detecting other analytes in CSF, and other body fluids.

Baronti C, Piorkowski G, Leparc-Goffart I, de Lamballerie X, Dubot-Pérès A. 2015. Rapid next-generation sequencing of dengue, EV-A71 and RSV-A viruses. J Virol Methods, 226 pp. 7-14. | Show Abstract | Read more

Accurate characterisation of viral strains constitutes a crucial objective for the management of modern virus collections. Next-generation sequencing (NGS) provides technical solution for fast and cost-effective full genome sequencing. Here, we report protocols for rapid full-genome characterisation of RNA viruses of medical importance: dengue virus, enterovirus A71 and respiratory syncytial virus A, based on a specific amplification step followed by NGS-sequencing. A subset of full-length genome sequences representing the genetic diversity of each virus type was selected in GenBank and used to design primer sets allowing the amplification of the complete genome in 3-8 overlapping PCR fragments. The technique was used for characterising 53 strains (33 DENV, 8 EV-A71, 12 RSV-A) from various genotypes and origins. In a single assay, and in just 4 days, it provided for all strains an excellent genomic coverage (∼ 99% including complete ORF for all strains) and accurate sequences with high number of reads per position (250-3500 on average). The elaboration of specific PCR-based full-genome sequencing protocols for diverse virus groups is likely to revolutionise the characterisation of viral isolates in modern collection, but also to contribute in the next future to the study of RNA viruses directly from biological samples.

Dubot-Pérès A, Sengvilaipaseuth O, Chanthongthip A, Newton PN, de Lamballerie X. 2015. How many patients with anti-JEV IgM in cerebrospinal fluid really have Japanese encephalitis? Lancet Infect Dis, 15 (12), pp. 1376-1377. | Read more

Mayxay M, Sengvilaipaseuth O, Chanthongthip A, Dubot-Pérès A, Rolain J-M, Parola P, Craig SB, Tulsiani S, Burns M-A, Khanthavong M et al. 2015. Causes of Fever in Rural Southern Laos. Am J Trop Med Hyg, 93 (3), pp. 517-520. | Show Abstract | Read more

The etiology of fever in rural Lao People's Democratic Republic (Laos) has remained obscure until recently owing to the lack of laboratory facilities. We conducted a study to determine the causes of fever among 229 patients without malaria in Savannakhet Province, southern Laos; 52% had evidence of at least one diagnosis (45% with single and 7% with apparent multiple infections). Among patients with only one diagnosis, dengue (30.1%) was the most common, followed by leptospirosis (7.0%), Japanese encephalitis virus infection (3.5%), scrub typhus (2.6%), spotted fever group infection (0.9%), unspecified flavivirus infection (0.9%), and murine typhus (0.4%). We discuss the empirical treatment of fever in relation to these findings.

Dittrich S, Sunyakumthorn P, Rattanavong S, Phetsouvanh R, Panyanivong P, Sengduangphachanh A, Phouminh P, Anantatat T, Chanthongthip A, Lee SJ et al. 2015. Blood-Brain Barrier Function and Biomarkers of Central Nervous System Injury in Rickettsial Versus Other Neurological Infections in Laos. Am J Trop Med Hyg, 93 (2), pp. 232-237. | Show Abstract | Read more

Blood-brain barrier (BBB) function and cerebrospinal fluid (CSF) biomarkers were measured in patients admitted to hospital with severe neurological infections in the Lao People's Democratic Republic (N = 66), including bacterial meningitis (BM; N = 9) or tuberculosis meningitis (TBM; N = 11), Japanese encephalitis virus (JEV; N = 25), and rickettsial infections (N = 21) including murine and scrub typhus patients. The albumin index (AI) and glial fibrillary acidic protein (GFAP) levels were significantly higher in BM and TBM than other diseases but were also raised in individual rickettsial patients. Total tau protein was significantly raised in the CSF of JEV patients. No differences were found between clinical or neurological symptoms, AI, or biomarker levels that allowed distinction between severe neurological involvement by Orientia tsutsugamushi compared with Rickettsia species.

Phommasone K, Sengvilaipaseuth O, de Lamballerie X, Vongsouvath M, Phonemixay O, Blacksell SD, Newton PN, Dubot-Pérès A. 2015. Temperature and the field stability of a dengue rapid diagnostic test in the tropics. Am J Trop Med Hyg, 93 (1), pp. 33-39. | Show Abstract | Read more

The global incidence of dengue has increased significantly in recent decades, resulting in a large public health burden in tropical and subtropical countries. Dengue rapid diagnostic tests (RDTs) can provide accurate, rapid accessible diagnosis for patient management and may be easily used by health workers in rural areas. However, in dengue-endemic areas, ambient temperatures are often higher than manufacturer's recommendation. We therefore evaluated the effect of high temperature over time on the performance of one commonly used dengue RDT, the Standard Diagnostics Bioline Dengue Duo. RDTs were kept in five different conditions (at 4°C, 35°C, 45°C, 60°C, and at fluctuant ambient temperatures in a free-standing hut) for between 2 days and 2 years in the Lao People's Democratic Republic (PDR). RDTs were tested with four control sera (negative, dengue nonstructural protein 1 [NS1], anti-dengue immunoglobulin [Ig] M, and anti-dengue IgG positive). The RDTs had 100% consistency over the 2-year study, despite high temperatures, including in the hut in which temperatures exceeded the manufacturer's recommendations for 29% of time points. These data suggest that the diagnostic accuracy of the SD Bioline Dengue Duo RDT remains stable even after long-term storage at high temperatures. Therefore, use at such ambient temperatures in tropical areas should not jeopardize the dengue diagnostic outcome.

Keita AK, Dubot-Pérès A, Phommasone K, Sibounheuang B, Vongsouvath M, Mayxay M, Raoult D, Newton PN, Fenollar F. 2015. High prevalence of Tropheryma whipplei in Lao kindergarten children. PLoS Negl Trop Dis, 9 (2), pp. e0003538. | Show Abstract | Read more

BACKGROUND: Tropheryma whipplei is a bacterium commonly found in feces of young children in Africa, but with no data from Asia. We estimated the prevalence of T. whipplei carriage in feces of children in Lao PDR (Laos). METHODS/PRINCIPAL FINDINGS: Using specific quantitative real-time PCR, followed by genotyping for each positive specimen, we estimated the prevalence of T. whipplei in 113 feces from 106 children in Vientiane, the Lao PDR (Laos). T. whipplei was detected in 48% (51/106) of children. Those aged ≤ 4 years were significantly less frequently positive (17/52, 33%) than older children (34/54, 63%; p< 0.001). Positive samples were genotyped. Eight genotypes were detected including 7 specific to Laos. Genotype 2, previously detected in Europe, was circulating (21% of positive children) in 2 kindergartens (Chompet and Akad). Genotypes 136 and 138 were specific to Chompet (21% and 15.8%, respectively) whereas genotype 139 was specific to Akad (10.55%). CONCLUSIONS/SIGNIFICANCE: T. whipplei is a widely distributed bacterium, highly prevalent in feces of healthy children in Laos. Further research is needed to identify the public health significance of this finding.

Dittrich S, Rattanavong S, Lee SJ, Panyanivong P, Craig SB, Tulsiani SM, Blacksell SD, Dance DAB, Dubot-Pérès A, Sengduangphachanh A et al. 2015. Orientia, rickettsia, and leptospira pathogens as causes of CNS infections in Laos: a prospective study. Lancet Glob Health, 3 (2), pp. e104-e112. | Show Abstract | Read more

BACKGROUND: Scrub typhus (caused by Orientia tsutsugamushi), murine typhus (caused by Rickettsia typhi), and leptospirosis are common causes of febrile illness in Asia; meningitis and meningoencephalitis are severe complications. However, scarce data exist for the burden of these pathogens in patients with CNS disease in endemic countries. Laos is representative of vast economically poor rural areas in Asia with little medical information to guide public health policy. We assessed whether these pathogens are important causes of CNS infections in Laos. METHODS: Between Jan 10, 2003, and Nov 25, 2011, we enrolled 1112 consecutive patients of all ages admitted with CNS symptoms or signs requiring a lumbar puncture at Mahosot Hospital, Vientiane, Laos. Microbiological examinations (culture, PCR, and serology) targeted so-called conventional bacterial infections (Streptococcus pneumoniae, Neisseria meningitidis, Haemophilus influenzae, S suis) and O tsutsugamushi, Rickettsia typhi/Rickettsia spp, and Leptospira spp infections in blood or cerebrospinal fluid (CSF). We analysed and compared causes and clinical and CSF characteristics between patient groups. FINDINGS: 1051 (95%) of 1112 patients who presented had CSF available for analysis, of whom 254 (24%) had a CNS infection attributable to a bacterial or fungal pathogen. 90 (35%) of these 254 infections were caused by O tsutsugamushi, R typhi/Rickettsia spp, or Leptospira spp. These pathogens were significantly more frequent than conventional bacterial infections (90/1051 [9%] vs 42/1051 [4%]; p<0·0001) by use of conservative diagnostic definitions. CNS infections had a high mortality (236/876 [27%]), with 18% (13/71) for R typhi/Rickettsia spp, O tsutsugamushi, and Leptospira spp combined, and 33% (13/39) for conventional bacterial infections (p=0·076). INTERPRETATION: Our data suggest that R typhi/Rickettsia spp, O tsutsugamushi, and Leptospira spp infections are important causes of CNS infections in Laos. Antibiotics, such as tetracyclines, needed for the treatment of murine typhus and scrub typhus, are not routinely advised for empirical treatment of CNS infections. These severely neglected infections represent a potentially large proportion of treatable CNS disease burden across vast endemic areas and need more attention. FUNDING: Wellcome Trust UK.

Nguyen VH, Sibounheuang B, Phommasone K, Vongsouvath M, Newton PN, Piorkowski G, Baronti C, de Lamballerie X, Dubot-Pérès A. 2014. First isolation and genomic characterization of enterovirus A71 and coxsackievirus A16 from hand foot and mouth disease patients in the Lao PDR. New Microbes New Infect, 2 (6), pp. 170-172. | Show Abstract | Read more

Enterovirus A71 (EV-A71) and coxsackievirus A16 (CV-A16) are major aetiological agents of hand, foot and mouth disease in Asia. We established the first genomic characterization of strains isolated in 2011 from Lao patients. Isolates were related to EV-A71 genotype C4 and CV-A16 genotype B1a that circulated in neighbouring countries during the same period. This confirms the regional character of hand, foot and mouth disease epidemiology and makes plausible the occurrence of severe disease in the Lao population.

Dittrich S, Phommasone K, Anantatat T, Panyanivong P, Slesak G, Blacksell SD, Dubot-Pérès A, Castonguay-Vanier J, Stenos J, Newton PN, Paris DH. 2014. Rickettsia felis Infections and comorbid conditions, Laos, 2003-2011. Emerg Infect Dis, 20 (8), pp. 1402-1404. | Read more

Bessaud M, Razafindratsimandresy R, Nougairède A, Joffret M-L, Deshpande JM, Dubot-Pérès A, Héraud J-M, de Lamballerie X, Delpeyroux F, Bailly J-L. 2014. Molecular comparison and evolutionary analyses of VP1 nucleotide sequences of new African human enterovirus 71 isolates reveal a wide genetic diversity. PLoS One, 9 (3), pp. e90624. | Show Abstract | Read more

Most circulating strains of Human enterovirus 71 (EV-A71) have been classified primarily into three genogroups (A to C) on the basis of genetic divergence between the 1D gene, which encodes the VP1 capsid protein. The aim of the present study was to provide further insights into the diversity of the EV-A71 genogroups following the recent description of highly divergent isolates, in particular those from African countries, including Madagascar. We classified recent EV-A71 isolates by a large comparison of 3,346 VP1 nucleotidic sequences collected from GenBank. Analysis of genetic distances and phylogenetic investigations indicated that some recently-reported isolates did not fall into the genogroups A-C and clustered into three additional genogroups, including one Indian genogroup (genogroup D) and 2 African ones (E and F). Our Bayesian phylogenetic analysis provided consistent data showing that the genogroup D isolates share a recent common ancestor with the members of genogroup E, while the isolates of genogroup F evolved from a recent common ancestor shared with the members of the genogroup B. Our results reveal the wide diversity that exists among EV-A71 isolates and suggest that the number of circulating genogroups is probably underestimated, particularly in developing countries where EV-A71 epidemiology has been poorly studied.

Ndille EE, Dubot-Pérès A, Doucoure S, Mouchet F, Cornelie S, Sidavong B, Fournet F, Remoue F. 2014. Human IgG antibody response to Aedes aegypti Nterm-34 kDa salivary peptide as an indicator to identify areas at high risk for dengue transmission: a retrospective study in urban settings of Vientiane city, Lao PDR. Trop Med Int Health, 19 (5), pp. 576-580. | Show Abstract | Read more

OBJECTIVE: Using human IgG antibody response to the Aedes Nterm-34 kDa salivary peptide as an indicator of human exposure to Aedes bites in surveying exposed populations from areas at risk of dengue virus (DENV) transmission in urban settings of Vientiane city, Lao PDR. METHODS: Enzyme-linked immunosorbent assay tests were performed to measure the IgG response to Nterm-34 kDa peptide in blood samples collected within a flavivirus seroprevalence survey carried out in 2006 including 3558 randomly selected individuals. The level of IgG response to the Nterm-34 kDa peptide in individuals was analysed in relation to the level of urbanisation of the individual's residence, areas that presented significant differences in the prevalence of recent DENV infection. RESULTS: No differences were observed in the anti-Nterm-34 kDa IgG level between DENV-positive and DENV-negative individuals. However, the level of specific IgG response was higher among individuals living in slightly urbanised neighbourhoods than among those in more highly urbanised areas (P < 0.0001). Interestingly, a similar pattern had already been observed concerning the prevalence of recent DENV infection in the same populations. CONCLUSION: The results of this retrospective study indicate that the evaluation of human IgG response to the Aedes Nterm-34 kDa salivary peptide could be a useful indicator to identify places with risk of dengue virus transmission in urban endemic areas.

Dubot-Pérès A, Tan CYQ, de Chesse R, Sibounheuang B, Vongsouvath M, Phommasone K, Bessaud M, Gazin C, Thirion L, Phetsouvanh R et al. 2014. SYBR green real-time PCR for the detection of all enterovirus-A71 genogroups. PLoS One, 9 (3), pp. e89963. | Show Abstract | Read more

Enterovirus A71 (EV-A71) has recently become an important public health threat, especially in South-East Asia, where it has caused massive outbreaks of Hand, Foot and Mouth disease every year, resulting in significant mortality. Rapid detection of EV-A71 early in outbreaks would facilitate implementation of prevention and control measures to limit spread. Real-time RT-PCR is the technique of choice for the rapid diagnosis of EV-A71 infection and several systems have been developed to detect circulating strains. Although eight genogroups have been described globally, none of these PCR techniques detect all eight. We describe, for the first time, a SYBR Green real-time RT-PCR system validated to detect all 8 EV-A71 genogroups. This tool could permit the early detection and shift in genogroup circulation and the standardization of HFMD virological diagnosis, facilitating networking of laboratories working on EV-A71 in different regions.

Mayxay M, Castonguay-Vanier J, Chansamouth V, Dubot-Pérès A, Paris DH, Phetsouvanh R, Tangkhabuanbutra J, Douangdala P, Inthalath S, Souvannasing P et al. 2013. Causes of non-malarial fever in Laos: a prospective study. Lancet Glob Health, 1 (1), pp. e46-e54. | Show Abstract | Read more

BACKGROUND: Because of reductions in the incidence of Plasmodium falciparum malaria in Laos, identification of the causes of fever in people without malaria, and discussion of the best empirical treatment options, are urgently needed. We aimed to identify the causes of non-malarial acute fever in patients in rural Laos. METHODS: For this prospective study, we recruited 1938 febrile patients, between May, 2008, and December, 2010, at Luang Namtha provincial hospital in northwest Laos (n=1390), and between September, 2008, and December, 2010, at Salavan provincial hospital in southern Laos (n=548). Eligible participants were aged 5-49 years with fever (≥38°C) lasting 8 days or less and were eligible for malaria testing by national guidelines. FINDINGS: With conservative definitions of cause, we assigned 799 (41%) patients a diagnosis. With exclusion of influenza, the top five diagnoses when only one aetiological agent per patient was identified were dengue (156 [8%] of 1927 patients), scrub typhus (122 [7%] of 1871), Japanese encephalitis virus (112 [6%] of 1924), leptospirosis (109 [6%] of 1934), and bacteraemia (43 [2%] of 1938). 115 (32%) of 358 patients at Luang Namtha hospital tested influenza PCR-positive between June and December, 2010, of which influenza B was the most frequently detected strain (n=121 [87%]). Disease frequency differed significantly between the two sites: Japanese encephalitis virus infection (p=0·04), typhoid (p=0·006), and leptospirosis (p=0·001) were more common at Luang Namtha, whereas dengue and malaria were more common at Salavan (all p<0·0001). With use of evidence from southeast Asia when possible, we estimated that azithromycin, doxycycline, ceftriaxone, and ofloxacin would have had significant efficacy for 258 (13%), 240 (12%), 154 (8%), and 41 (2%) of patients, respectively. INTERPRETATION: Our findings suggest that a wide range of treatable or preventable pathogens are implicated in non-malarial febrile illness in Laos. Empirical treatment with doxycycline for patients with undifferentiated fever and negative rapid diagnostic tests for malaria and dengue could be an appropriate strategy for rural health workers in Laos. FUNDING: Wellcome Trust, WHO-Western Pacific Region, Foundation for Innovative New Diagnostics, US Centers for Disease Control and Prevention

Dubot-Pérès A, Vongphrachanh P, Denny J, Phetsouvanh R, Linthavong S, Sengkeopraseuth B, Khasing A, Xaythideth V, Moore CE, Vongsouvath M et al. 2013. An epidemic of dengue-1 in a remote village in rural Laos. PLoS Negl Trop Dis, 7 (8), pp. e2360. | Show Abstract | Read more

In the Lao PDR (Laos), urban dengue is an increasingly recognised public health problem. We describe a dengue-1 virus outbreak in a rural northwestern Lao forest village during the cool season of 2008. The isolated strain was genotypically "endemic" and not "sylvatic," belonging to the genotype 1, Asia 3 clade. Phylogenetic analyses of 37 other dengue-1 sequences from diverse areas of Laos between 2007 and 2010 showed that the geographic distribution of some strains remained focal overtime while others were dispersed throughout the country. Evidence that dengue viruses have broad circulation in the region, crossing country borders, was also obtained. Whether the outbreak arose from dengue importation from an urban centre into a dengue-naïve community or crossed into the village from a forest cycle is unknown. More epidemiological and entomological investigations are required to understand dengue epidemiology and the importance of rural and forest dengue dynamics in Laos.

Aubry F, Vongsouvath M, Nougairède A, Phetsouvanh R, Sibounheuang B, Charrel R, Rattanavong S, Phommasone K, Sengvilaipraserth O, de Lamballerie X et al. 2013. Complete Genome of a Genotype I Japanese Encephalitis Virus Isolated from a Patient with Encephalitis in Vientiane, Lao PDR. Genome Announc, 1 (1), pp. e00157-12-e00157-12. | Show Abstract | Read more

Japanese encephalitis virus (JEV) (Flaviviridae, Flavivirus) is an arthropod-borne flavivirus transmitted by Culex species mosquitoes. We report here the complete genome of the JEV genotype I strain JEV_CNS769_Laos_2009 isolated from an infected patient in Vientiane, Lao People's Democratic Republic (PDR) (Laos).

Tan CYQ, Gonfrier G, Ninove L, Zandotti C, Dubot-Pérès A, de Lamballerie X, Charrel RN. 2012. Screening and detection of human enterovirus 71 infection by a real-time RT-PCR assay in Marseille, France, 2009-2011. Clin Microbiol Infect, 18 (4), pp. E77-E80. | Show Abstract | Read more

Enterovirus-positive samples diagnosed in Marseille (January 2009 to September 2011) were screened for EV71 by real-time RT-PCR. EV71 was detected in three children below the age of 2 years with no history of overseas travel; two of these cases were associated with severe clinical presentation. Viruses demonstrated genetic similarity to other European genogroup C2 strains. Strain MRS/09/3663 complete sequencing revealed 97.6% identity across the entire genome with a 2008 Singapore isolate, without signs of possible recombination events. To our knowledge, this is the first detection of EV71 infection in Marseille, France, that confirms the current circulation of EV71 in France.

Vallée J, Dubot-Pérès A, Ounaphom P, Sayavong C, Bryant JE, Gonzalez J-P. 2009. Spatial distribution and risk factors of dengue and Japanese encephalitis virus infection in urban settings: the case of Vientiane, Lao PDR. Trop Med Int Health, 14 (9), pp. 1134-1142. | Show Abstract | Read more

OBJECTIVES: To evaluate the prevalence of flavivirus infection in Vientiane city (Lao PDR), to describe the spatial distribution of infection within this city, and to explore the link between flavivirus seroprevalence and urbanization levels of residential neighbourhoods. METHODS: A seroprevalence survey was carried out in 2006 including 1990 adults (>or=35 years) and 1568 children (>or=6 months and <6 years) randomly selected. RESULTS: The prevalence of individuals with previous flavivirus infection (i.e. negative for both DEN and JE IgM but positive for DEN IgG) was 57.7%, with a significantly (P < 0.001) higher prevalence among adults (84.6%; 95% confidence interval (CI) = 82.4-86.8) than children (9.4%; 95% CI = 7.2-11.6). The prevalence of individuals with recent flavivirus infection (i.e. positive for DEN and/or JE IgM) was 6.5% and also significantly (P < 0.001) higher among adults (10.0%; 95% CI = 8.3-11.7) than children (2.5%; 95% CI = 1.5-3.5). In terms of spatial distribution, IgG prevalence was significantly (P < 0.001) higher among individuals living in the central city (60.1%; 95% CI = 56.2-64.1) than among those living in the periphery (44.3%; 95% CI = 41.5-47.2). In contrast, seroprevalence of recent flavivirus infections was significantly (P < 0.001) higher among individuals living in the periphery (8.8%; 95% CI = 6.9-10.7) than in the central city (4.0%; 95% CI = 2.9-5.2). This association was also statistically consistent (P < 0.01) in multivariate logistic regression after controlling for individual risk factors. CONCLUSIONS: Our findings indicate that the level of urbanization of residential neighbourhoods influences the risk of flavivirus infection. The spatial distribution of flavivirus infection varies, even within a small city of less than 300,000 habitants such as Vientiane.

Nitatpattana N, Dubot-Pérès A, Gouilh MA, Souris M, Barbazan P, Yoksan S, de Lamballerie X, Gonzalez J-P. 2008. Change in Japanese encephalitis virus distribution, Thailand. Emerg Infect Dis, 14 (11), pp. 1762-1765. | Show Abstract | Read more

Japanese encephalitis virus (JEV) genotypes in Thailand were studied in pigs and mosquitoes collected near houses of confirmed human JEV cases in 2003-2005. Twelve JEV strains isolated belonged to genotype I, which shows a switch from genotype III incidence that started during the 1980s.

Barbazan P, Thitithanyanont A, Missé D, Dubot A, Bosc P, Luangsri N, Gonzalez J-P, Kittayapong P. 2008. Detection of H5N1 Avian Influenza Virus from Mosquitoes Collected in an Infected Poultry Farm in Thailand Vector-Borne and Zoonotic Diseases, 8 (1), pp. 105-110. | Read more

Grard G, Lemasson J-J, Sylla M, Dubot A, Cook S, Molez J-F, Pourrut X, Charrel R, Gonzalez J-P, Munderloh U et al. 2006. Ngoye virus: a novel evolutionary lineage within the genus Flavivirus. J Gen Virol, 87 (Pt 11), pp. 3273-3277. | Show Abstract | Read more

By using degenerate primers deduced from conserved patterns in the flavivirus polymerase gene, a novel RNA virus was discovered in Rhipicephalus ticks sampled from members of the family Bovidae in Senegal. It was named Ngoye virus (NGOV) after the location from which it was isolated. Viral particles could be observed by electron microscopy, but isolation in vertebrate or invertebrate cell lines or by intracerebral infection of newborn mice remained unsuccessful. This is atypical of recognized arboviruses. The characterization of 4176 nt of the non-structural genes revealed that NGOV is a novel flavivirus species. It forms a distinct phylogenetic lineage related distantly to previously identified members of the genus Flavivirus. Analysis of genetic data suggested that the processing of the NGOV polyprotein and the organization of its replication complex are similar to those of flaviviruses. Together with other recent data, these findings suggest that a large number of viruses related distantly to 'classical' arthropod-borne flaviviruses remain to be discovered.

DUBOT A. 2004. Pathogenicity of missense mutations in SURF1 deficiency inducing the Leigh syndrome. Importance in diagnosis Mitochondrion, 4 (1), pp. 41-47. | Read more

Vojtíšková A, Ješina P, Kalous M, Kaplanová V, Houštěk J, Tesařová M, Fornůsková D, Zeman J, Dubot A, Godinot C. 2004. Mitochondrial Membrane Potential and ATP Production in Primary Disorders of ATP Synthase Toxicology Mechanisms and Methods, 14 (1-2), pp. 7-11. | Read more

Pecina P, Čapková M, Chowdhury SKR, Drahota Z, Dubot A, Vojtíšková A, Hansíková H, Houšt'ková H, Zeman J, Godinot C, Houštěk J. 2003. Functional alteration of cytochrome c oxidase by SURF1 mutations in Leigh syndrome Biochimica et Biophysica Acta (BBA) - Molecular Basis of Disease, 1639 (1), pp. 53-63. | Read more

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