Annals of Tropical Medicine & Parasitology, Vol. 95, No. 4, 395± 398 (2001) Serological evidence for the continued presence of human rickettsioses in southern India BY E. MATHAI* Department of Clinical Microbiology, Christian Medical College Hospital, Vellore, Tamil Nadu 632004, India G. LLOYD Diagnosis and Reference, Special Pathogens, Centre for Applied Microbiological Research, Porton Down, Salisbury SP4 0JQ, U.K. T. CHERIAN Department of Child Health, Christian Medical College Hospital, Vellore, Tamil Nadu 632004, India O. C. ABRAHAM AND A. M. CHERIAN Department of Medicine, Christian Medical College Hospital, Vellore, Tamil Nadu 632004, India Received 28 July 2000, Revised and accepted 30 April 2001 Rickettsiosis is generally believed to have disappeared from many parts of India. However, the serological testing of 37 residents of southern India who presented with fever of unknown aetiology in 1996± 1998 con® rmed that spotted fever, epidemic/endemic typhus and scrub typhus continue to occur in southern India. The epidemiology and magnitude of the problem need to be evaluated. In the past, rickettsial infections of several types occurred in the human residents of India. Epidemic typhus (caused by Rickettsia prowazekii), for example, was largely restricted to hilly terrain in the north± west of the sub- continent whereas endemic or murine typhus (R. typhi) and Indian tick typhus (R. conorii) used to occur in many states, and there were epidemics of scrub typhus (Orientia tsutsuga- mushi) among the troops stationed in northern and eastern areas (Varma and Mahadevan, 1972; Padbidri and Gupta, 1978; Shanmugam et al., 1978; Padbidri et al., 1980; Kumar et al., 1982; Maniya et al., 1988; Jayaseelan et al., 1991). However, the availability of effective treatments for these diseases and the killing of many of the vectors (as a side-effect of the widespread use of insecticides to control other vector-borne infections) has recently led to massive reductions in the incidence of rick- ettsioses in many areas (Padbidri and Gupta, 1978). Although sporadic cases continue to be reported, a general lack of awareness and of speci® c tests to identify the rickettsial species involved has meant that very little information is available on the current status of these infections in India. The Weil± Felix (WF) agglutination test, popularized by the Indian army in the 1930s, continues to be the only test available in most medical institutions in India, although a positive result in this test only indicates a rickettsial infection and not * E-mail: mathaim@cmcvellore.ac.in. ISSN 0003-4983 (print) ISSN 1364-8594 (online)/01/040395-04 Ó 2001 Liverpool School of Tropical Medicine Carfax Publishing DOI: 1080/00034980120065804