Orientia tsutsugamushi (from Japanese tsutsuga meaning “illness”, and mushi meaning “insect”) is a mite-borne bacterium and is responsible for a disease called scrub typhus in humans.
The disease, scrub typhus, occurs when infected mite larvae accidentally bite humans. Primarily indicated by undifferentiated febrile illnesses, the infection can be complicated and often fatal.
Scrub typhus is historically endemic to the Asia-Pacific region, covering the Russian Far East and Korea in the north, to northern Australia in the south, and Afghanistan in the west, including islands of the western Pacific Oceans such as Japan, Taiwan, Philippines, Papua New Guinea, Indonesia, Sri Lanka, and the Indian Subcontinent. However, it has spread to Africa, Europe and South America.
The main symptom of O. tsutsugamushi infection is high (febrile) fever; however, the symptom is similar to other vector-borne tropical diseases such as malaria, leptospirosis, typhoid, murine typhus, chikungunya, and dengue fever. This makes precise clinical diagnosis difficult, which often leads to misdiagnosis.