Scrub Typhus Diagnostics: The Present and the Future

Scrub typhus, caused by Orientia tsutsugamushi , is a vector-borne, zoonotic disease commonly occurring in a geographic region known as the ‘tsutsugamushi triangle’. Scrub typhus causes acute undifferentiated febrile illness (AUFI) with non-specific clinical features and is difficult to diagnose when a highly characteristic but not pathognomonic eschar is absent. Because the eschar is not always present, laboratory tests are required for diagnosis. Serological assays have been the mainstay of laboratory diagnosis of scrub typhus to date. Here, we present the major clinical features and clinical algorithms suggestive of this disease, to aid in better selection of diagnostic methods. The advantages and disadvantages of various scrub typhus assays are also discussed. Furthermore, we describe diagnostics, including serological and molecular assays, that may be available in the near future.