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 <15 years; 53% were female. The epidemic curve showed a propagated pattern with a peak in IDSP week 9 (early March). Household attack rate was 11.4%. Clinical presentation was consistent with varicella: rash (100%), weakness and body ache (100%), fever (97%). Of six specimens, four were VZV IgM positive (67%), one equivocal and one negative. No severe complications or deaths occurred. This investigation confirmed a propagated varicella outbreak in a rural Jharkhand village, largely affecting children and young adults. Rapid detection through IDSP/IHIP and field investigation by an FETP-trained team facilitated timely control through case isolation, community education and symptomatic management.