Vibrio Cholerae O1 Transmission in Bangladesh: Insights from a Nationally-Representative Serosurvey

Background Pandemic Vibrio cholerae from cholera-endemic countries around the Bay of Bengal regularly seed epidemics globally. Without reducing cholera in these countries, including Bangladesh, global cholera control may never be achieved. Little is known about the geographic distribution and magnitude of V. cholerae O1 transmission nationally. Here we use recent advances in cholera seroepidemiology to describe infection risk across Bangladesh overcoming many of the limitations of current clinic-based surveillance. Methods We tested serum from a nationally-representative serosurvey in Bangladesh of 2,778 participants with eight V. cholerae -specific assays. Using these data with a previously validated machine learning model we estimate the annual seroincidence rate and use Bayesian geostatistical models to create high-resolution national maps of infection risk. Findings We estimate a national seroincidence rate of 19.1% (95% CI 12.2-26.9%). Our high-resolution maps reveal large heterogeneity of infection risk, with community-level annual infection risk within the sampled population ranging from 2.4-69.0%. Across the country, we estimate that 31.0 million (95% CI 19.8-43.7 million) occurred in the year before the survey with most of these infections occurring in urban areas, including Dhaka, the capital. Interpretation Serosurveillance provides an avenue for identifying areas with high V. cholerae O1 transmission and exploring key risk factors for infection across geographic scales. This may serve as an important tool for countries to plan and monitor progress towards 2030 cholera elimination goals.