Rickettsioses and Zoonoses

Rickettsioses, or rickettsial illnesses, consist of a diverse group of zoonotic infectious diseases caused by obligate intracellular bacteria grouped in the order Rickettsiales, which includes the genera Rickettsia, Orientia, Ehrlichia, Anaplasma, Neorickettsia and Wolbachia.


Rickettsial diseases are seriously under-recognised and under-studied public health problems in Asia. In rural areas they may be the most common treatable cause of fever.

In 1999, the World Health Organization (WHO) stated that; "Scrub typhus is probably the most under diagnosed and under reported febrile illnesses requiring hospitalization in the region [Southeast Asia]."

The wide (and expanding) geographic distribution of rickettsial illnesses and the high percentage of rickettsial etiologies among patients with undifferentiated febrile illness in Southeast Asia, are strong indicators that the true incidence of rickettsial diseases remains under appreciated.