Scrub typhus

Scrub typhus is an acute febrile illness caused by the bacterium Orientia tsutsugamushi. The bacterium is transmitted by mites from the genus Leptotrombidium. Scrub typhus lacks differentiating clinical features, making it difficult to diagnose without sophisticated laboratory tests. If not treated, the median mortality has been reported to be 6% and may reach up to 70%. 

Chinese epidemiologists collect data in the form of specimens during an epidemiological rickettsial investigation. Credit: CDC, Jessie Blount
Chinese epidemiologists collect data in the form of specimens during an epidemiological rickettsial investigation. Credit: CDC, Jessie Blount

Although over one billion people are at risk of scrub typhus, compared to its magnitude, evidence to optimise treatments and disease control is sparse. The currently available diagnostic methods for scrub typhus are either culture, serology, or molecular based and require relatively sophisticated infrastructures, which is not always accessible in resource limited settings. The difficulty in diagnosing scrub typhus contributes to the scant data available to estimate its burden. It also makes timely diagnosis challenging. Although scrub typhus is treatable with antibiotics, delayed treatment could be fatal.

Trials informing scrub typhus treatments are few and often with small sample sizes. Tetracyclines, chloramphenicol, azithromycin, and rifampicin seem to be effective. However, cases resistant to chloramphenicol and doxycycline have been reported in northern Thailand.

IPD Platform Scoping and Feasibility Study

One way to facilitate evaluation of the efficacy of scrub typhus treatments is through establishing an individual-level participant data (IPD) platform covering global treatment studies data. This will allow standardisation and pooling of the scattered global data.

To explore the needs and feasibility of developing a scrub typhus IPD platform, IDDO in collaboration with MORU are performing a systematic review to assess the landscape of the available scrub typhus treatment studies (PROSPERO CRD42018089405).

This systematic review aims to summarise the characteristics of prospective treatment studies such as study types, participant numbers, and outcomes. Through exploring these characteristics, we can develop our understanding on the quality and heterogeneity of the available data. In addition, these existing data can be a source of information to address research priorities and knowledge gaps.

If feasible and there are needs to establish a scrub typhus IPD platform, this would require extensive collaboration from stakeholders and leaders of the scrub typhus research community. We are looking to engage as early as possible to understand the needs of the research community and policy makers, and to ensure that the development of the IPD platform can fulfill these needs. For further information on this project, please contact

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The Mahidol Oxford Tropical Medicine Research Unit (MORU) develops effective and practical means of diagnosing and treating malaria and other neglected diseases such as melioidosis, typhus, TB and leptospirosis. 

MORU was established in 1979 as a research collaboration between Mahidol University (Thailand), Oxford University (UK) and the UK’s Wellcome Trust.

MORU’s main office and laboratories are located within the Faculty of Tropical Medicine at Mahidol University in Bangkok, Thailand, with MORU study sites and collaborations across Thailand, Asia and Africa.