Rickettsiosis as a critical emerging infectious disease in India

Abstract

Gram-negative bacteria belonging to the order Rickettsiales such as Anaplasma, Ehrlichia, Neorickettsia, Rickettsia, and Orientia are the causative agents of infectious diseases collectively known as rickettsioses. Of the different rickettsial diseases, spotted fever and scrub typhus have ravaged India for the past couple of centuries. Specifically called the Indian tick typhus, spotted fever was discovered in India in the latter half of the 19th century. After several decades of dormancy, the disease re-emerged in several parts of India. Scrub typhus, originally discovered in Japan, has been recognised to be endemic to a so-called Tsutsugamushi Triangle, extending from Russian Far East and Korea in the north to northern Australia in the south and Afghanistan in the west, but the geographical description has now been breached. Not only in India, scrub typhus has emerged as the leading infectious disease in all endemic areas. Almost all Indian states have records of recurrent outbreaks. Infection can be of dire consequences, as multi-organ dysfunction and neurological disorder (meningocephalitis) are the common complications. This article discusses the historical background and scientific reports of rickettsioses in India.