Orientia

Orientia spp. are obligate intracellular Gram-negative bacteria, with Leptotrombidium mites acting as both reservoirs and transmission vectors. The disease, caused by Orientia spp. (commonly called scrub typhus) is characterised by early non-specific ‘flu-like’ symptoms, and sometimes a diffuse, macular and/or maculopapular rash and/or an eschar at the mite bite site. Complicated scrub typhus includes meningoencephalitis, respiratory and renal failure, which can develop into severe multiorgan failure. Scrub typhus is the leading cause of undifferentiated febrile illness in many regions of Asia. Despite its treatable nature, scrub typhus remains an underappreciated, neglected disease, mainly due to diagnostic difficulties and lack of awareness among medical staff. The development of diagnostics and vaccines difficulties challenging, due to the immunogenic diversity of Orientia strains, the weak and transient cross-protection among divergent isolates, and the loss of heterologous protection within a few years after natural infection.