Scrub typhus in urban areas of Wardha district in central India

BACKGROUND & OBJECTIVES: Scrub typhus caused by Orientia tsutsugamushi presents as acute undifferentiated fever and can be confused with other infectious causes of fever. We studied scrub typhus as part of a study on hospital-based surveillance of zoonotic and vector-borne zoonotic diseases at a tertiary care hospital located in the Wardha district, Maharashtra, India. We report here descriptive epidemiology and climatic factors affecting scrub typhus. METHODS: Patients of any age and sex with fever of ≥5 days were enrolled for this study. Data on sociodemographic variables were collected by personal interviews. Blood samples were tested by IgM ELISA to diagnose scrub typhus. Confirmation of scrub typhus was done by indirect immunofluorescence assay for IgM (IgM IFA). The climatic determinants were determined using time-series Poisson regression analysis. RESULTS: It was found that 15.9 per cent of the study participants were positive for scrub typhus by IgM ELISA and IgM IFA, both. Positivity was maximum (23.0%) in 41-60 yr of age and more females were affected than males (16.6 vs. 15.5%). Farmworkers were affected more (23.6%) than non-farm workers (12.9%). The disease positivity was found to be high in monsoon and post-monsoon seasons (22.9 and 19.4%) than in summer and winter. INTERPRETATION & CONCLUSIONS: There were three hot spots of scrub typhus in urban areas of Wardha district. Rainfall and relative humidity in the previous month were the significant determinants of the disease.