Investigation of an outbreak of scrub typhus in the himalayan region of India.

In Indira Gandhi Medical College, Himachal Pradesh, India, during autumn of 2003 (September-November), more than 100 cases of fever of unknown origin (FUO) were reported with 15 ensuing deaths. In addition to all routine investigations and cultures, the Weil-Felix test was incorporated for the investigation of these cases. Antigen was procured from the Central Research Institute, Kasauli. Forty-six percent (45/96) of the cases demonstrated a > or =1:80 titer of agglutinins against OXK antigen. A team from the National Institute of Communicable Diseases, New Delhi, confirmed the antibodies for scrub typhus in some of the serum samples tested for leptospirosis, dengue fever, and rickettsial infections. Twelve blood samples positive for OXK antigen were sent to the Defense Research Development Establishment, Gwalior, for polymerase chain reaction studies, but none of the samples were positive, as all of the patients were already on broad-spectrum antibiotics and had reported to our hospital after 7-10 days of fever. At our institute, the Weil-Felix test has now been rountinely introduced for the investigation of cases of FUO, and the results until April 2004 (150 cases) revealed the presence of other rickettsial infections prevalent in the region. To evaluate the epidemiology and magnitude of the problem, further prospective studies are required.