Abstract

Chickenpox (varicella) outbreaks occur in settings with low immunity, overcrowding, or poor vaccination coverage. In March 2025, a cluster of febrile rash illness was reported from Manda village, Dumaria block, Purbi Singhbhum district, Jharkhand, India. Investigation was done to confirm the diagnosis, describe the epidemiology, and recommend control measures. A rapid response team led by the district epidemiologist (Field Epidemiology Training Program [FETP] trained) conducted a descriptive outbreak investigation. Investigation involved enhanced surveillance (house-to-house search), facility registers review, and interview of key informants. Case definitions (suspected, probable, confirmed) adapted from IDSP/WHO were used. Six specimens were sent for VZV IgM ELISA. Data was analyzed to produce an epidemic curve, age- and sex-specific attack rates, household attack rates, and spot-map clustering. Between 24 January and 19 March 2025, 34 cases (attack rate 5.1% of the village population of 672) were identified. Median age was 14 years (IQR 7–28); 50% were

Key words: Chickenpox, Epidemiology, Outbreak, Surveillance, Varicella