Large-scale systematic review identifies research gaps in scrub typhus

The paper, Systematic review of the scrub typhus treatment landscape: Assessing the feasibility of an individual participant-level data (IPD) platform pooling and analysing individual participant-level data (IPD), screened 3,100 articles published between 1998 and 2020, and included 127 clinical treatment studies representing 12,079 patients from 12 countries. Researchers found there were a limited number of interventional trials, highlighting that scrub typhus remains a neglected disease.

Scrub typhus is an acute febrile illness caused by intracellular bacteria from the genus Orientia. It is estimated that one billion people are at risk, with one million cases annually mainly affecting rural areas in Asia-Oceania. Scrub typhus is difficult to diagnose clinically without laboratory tests because it lacks reliable distinguishing features that differentiate it from other febrile illnesses prevalent in the endemic areas, such as typhoid fever, dengue fever and malaria. This difficulty in diagnosis is one of the main reasons for the current limited epidemiological knowledge on scrub typhus.

With scant and scattered data, it is difficult to identify the most at-risk populations, the regional distribution, and the optimal treatments to support disease control efforts. National treatment recommendations for scrub typhus vary or are simply not stated, and the absence of WHO recommendations illustrates the lack of high-quality supportive evidence for optimal treatments.

The authors have called for scrub typhus to be recognised as a neglected tropical disease (NTD) by the WHO and the research community, which will help to increase awareness of the disease.

Researchers concluded there is substantial value in developing an IPD platform that will facilitate pooling and harmonisation of currently scattered data and enable in-depth investigation of priority research questions that can ultimately inform clinical practice and improve health outcomes for scrub typhus patients.

First author Kartika Saraswati said: “The heterogeneous nature of the available data reflects the absence of consensus in treatment and research methodologies and poses a significant barrier to aggregating information across available published data without access to the underlying individual participant-level data (IPD). There is likely to be a substantial amount of data available to address knowledge gaps.”