Investigation of fatal chickenpox outbreak among adults in Northern Bangladesh, 2023.

Objectives: Although chickenpox is usually mild and self-limiting, severe complications and death may occur among adults. In April 2023, two adult deaths associated with clinically diagnosed chickenpox in a remote village of northern Bangladesh triggered notification of a suspected outbreak and prompted an investigation to describe its epidemiologic characteristics and contextual factors associated with severe adult cases. Methods: A mixed-method outbreak investigation was conducted from April 15-19, 2023 in Thakurgaon district. Active case finding, household visits, line listing, and verbal autopsies were performed. Vesicular swabs were tested for varicella-zoster virus (VZV) by polymerase chain reaction (PCR). Environmental assessments and a focus group discussion explored contextual factors, community perceptions, and care-seeking behavior. Results: A total of 23 confirmed cases were identified, including seven laboratory-confirmed cases. The attack rate was 1.2% and the case fatality rate 8.7%. Adults over the age of 20 years comprised 52.2% of cases and males 60.9%. Both fatal cases were adult males with comorbidities, heavy smoking history, delayed care-seeking, pneumonia, and thrombocytopenia. All samples were PCR-positive for VZV. The epidemic curve suggested propagated transmission. Qualitative findings indicated reliance on traditional healers and delayed formal care. Conclusion: Chickenpox can result in severe and fatal outcomes among adults in resource-limited settings. Early recognition and timely health care access are critical to reducing mortality.