Scrub typhus in northern Thailand

Scrub typhus is an infection caused by Orientia tsutsugamushi, a bacteria transmitted by the bite of an infected chigger mite. Characterised by a variety of symptoms and a high mortality rate, scrub typhus is an underfunded, neglected tropical disease not even listed by the WHO. Better diagnostic tests and optimised treatments are being developed since no vaccine is currently available.

View podcast transcript

Before returning to Oxford and clinical work as an infectious diseases and microbiology doctor in February 2020, I was the head of the MORU-affiliated satellite tropical medicine research unit in Chiangrai, Thailand, for 5 years. It is situated in the most northern province of the country bordering Myanmar and Laos. The region's topography is a mixture of hilly and riverine habitats. The population comprises Thais as well as groups belonging to hilltribes and migrant workers from neigbouring countries.

Chiangrai is located in a region endemic for tropical rickettsioses with scrub typhus being a major cause of febrile illness. Although it remains easily treatable with available antibiotics, much of the morbidity and mortality from scrub typhus can be derived from delayed presentation, lack of recognition, and limited access to effective diagnostics. All these factors contribute to a significant health burden not only locally, but also to the wider Asia-Pacific region where it is estimated that a billion people are at risk. Furthermore, there remain uncertainties about the optimal treatment of scrub typhus in Chiangrai, an area where drug-resistant strains of Orientia tsutsugamushi, a Gram negative intracellular bacteria responsible for scrub typhus, were previously reported over 2 decades ago. This finding is yet to be validated and the underlying nature fully investigated.

My thesis, “Scrub typhus in northern Thailand”, explores the epidemiology of scrub typhus, the contribution of scrub typhus to the acute febrile disease burden in adults admitted to hospital, paediatric scrub typhus and antibiotic treatment along with determinants of treatment outcome. 

Prof Nicholas Day

Prof Paul Newton

Prof Joel Tarning

Prof Mavuto Mukaka