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.
- Scrub typhus, caused by Orientia tsutsugamushi, and murine typhus caused by Rickettsia typhi account for up to 30% of malaria-negative fevers in rural Thailand and Laos
- In Southeast Asia alone, an estimated 1 million cases of scrub typhus occur annually, which - based on available limited mortality rates - translates into approximately 50,000 to 80,000 deaths per year, which is almost certainly an underestimation
- Scrub typhus and murine typhus together probably represent the most frequent, neglected but treatable infections in the world
- Unfortunately, treatment delays due to lack of appropriate diagnostics and awareness lead to a substantial health and economic impact in the world’s most densely populated regions
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.