A Review of Rickettsial Diseases Other Than Scrub Typhus in India

Abstract

Rickettsial diseases (RD) are widely reported all over the world. Scrub typhus (ST) is a major tropical infection which is well documented all over India. Therefore, the index of suspicion of scrub typhus is high among physicians with regard to patients presenting with acute febrile illness (AFI) and acute undifferentiated febrile illness (AUFI) in India. Rickettsial diseases other than ST (non-ST RDs), which include spotted fever group (SFG) rickettsioses and typhus group (TG) rickettsioses are not uncommon in India, but the index of suspicion is not as high as ST unless there is a history of the presence of fever with rashes and/or recent arthropod bites. This review aims to look into the Indian scenario on the epidemiology of non-ST RDs, especially the SFG and TG rickettsioses based on various investigations, spectrum of clinical presentation, challenges and gaps in knowledge to suspect and diagnose these infections.

Molecular Evidence of Rickettsia conorii subsp. raoultii and Rickettsia felis in Haemaphysalis intermedia Ticks in Sirumalai, Eastern Ghats, Tamil Nadu, South India

“…Tick-borne rickettsioses are mainly caused by the SFG; its identification at the species level with immunological methods is difficult since ticks are a more competent and versatile vector [ 9 ]. The studies on spotted fever group (SFG) and typhus group (TG) rickettsioses are limited when compared with Scrub typhus (ST) [ 10 ]. However, worldwide, improved diagnostic methods have contributed to the reliable identification of tick-borne pathogens (TBP) in humans, domestic animals and vectors [ 11 ].…”

“…Though outbreaks due to rickettsial etiology have been well documented in many Indian states [ 20 ], the available data on the circulation of Rickettsia through serological and molecular evidence and their clinical relevance in causing illness in humans is very scanty, but this evidence confirms its widespread distribution in the country [ 21 , 22 , 23 ]. The recent reports of encephalitis cases due the rickettsial infection spread by ectoparasites stress attention to molecular diagnosis SFG and TG because only >10% outbreaks of acute encephalitis syndrome (AES) etiology were confirmed and the reaming is not confirmed with molecular methods [ 10 ].…”

The Molecular Detection of Bacterial Infections of Public Health Importance in Hard Tick (Ixodidae) Nymphs Collected from the Forest Fringes of Western Ghats in the Goa, Karnataka and Maharashtra States of India

“…and Coxiella burnetii . are particularly prevalent in humans [ 2 , 3 ]. Tick bites are more commonly encountered by individuals residing in rural areas and those living on the fringes of forests.…”