Abstract
SummaryBackgroundPandemic 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 might never be achieved. Little is known about the geographical distribution and magnitude of V cholerae O1 transmission nationally. We aimed to describe infection risk across Bangladesh, making use of advances in cholera seroepidemiology, therefore overcoming many of the limitations of current clinic-based surveillance.MethodsWe tested serum samples from a nationally representative serosurvey in Bangladesh with eight V cholerae-specific assays. Using these data with a machine-learning model previously validated within a cohort of confirmed cholera cases and their household contacts, we estimated the proportion of the population with evidence of infection by V cholerae O1 in the previous year (annual seroincidence) and used Bayesian geostatistical models to create high-resolution national maps of infection risk.FindingsBetween Oct 16, 2015, and Jan 24, 2016, we obtained and tested serum samples from 2930 participants (707 households) in 70 communities across Bangladesh. We estimated national annual seroincidence of V cholerae O1 infection of 17·3% (95% CI 10·5–24·1). Our high-resolution maps showed large heterogeneity of infection risk, with community-level annual infection risk within the sampled population ranging from 4·3% to 62·9%. Across Bangladesh, we estimated that 28·1 (95% CI 17·1–39·2) million infections occurred in the year before the survey. Despite having an annual seroincidence of V cholerae O1 infection lower than much of Bangladesh, Dhaka (the capital of Bangladesh and largest city in the country) had 2·0 (95% CI 0·6–3·9) million infections during the same year, primarily because of its large population.InterpretationSerosurveillance provides an avenue for identifying areas with high V cholerae O1 transmission and investigating key risk factors for infection across geographical scales. Serosurveillance could serve as an important method for countries to plan and monitor progress towards 2030 cholera elimination goals.FundingThe Bill & Melinda Gates Foundation, National Institutes of Health, and US Centers for Disease Control and Prevention.
Highlights
As the seventh cholera pandemic approaches its 60th year, the global public health community is making plans to end cholera as a public health threat by 2030, through reducing transmission and nearly eliminating cholera mortality.[1]
We tested serum samples from a nationally representative serosurvey in Bangladesh with eight V choleraespecific assays. Using these data with a machine-learning model previously validated within a cohort of confirmed cholera cases and their household contacts, we estimated the proportion of the population with evidence of infection by V cholerae O1 in the previous year and used Bayesian geostatistical models to create highresolution national maps of infection risk
These aspirations are challenged by new lineages of pandemic Vibrio cholerae O1 that repeatedly arise in south Asia and spread worldwide, seeding local and regional epidemics that can last decades, including massive contemporary outbreaks in Haiti and Yemen.[2,3,4,5]
Summary
As the seventh cholera pandemic approaches its 60th year, the global public health community is making plans to end cholera as a public health threat by 2030, through reducing transmission and nearly eliminating cholera mortality.[1] these aspirations are challenged by new lineages of pandemic Vibrio cholerae O1 that repeatedly arise in south Asia and spread worldwide, seeding local and regional epidemics that can last decades, including massive contemporary outbreaks in Haiti and Yemen.[2,3,4,5] Without a substantial reduction in cholera transmission in highly endemic countries around the Bay of Bengal, such as Bangladesh, V cholerae dissemination to other parts of the world will continue, and global cholera control might never be achieved. Most surveillance efforts have focused on a few sites within the country, including the sentinel icddr,b hospital in Dhaka and the Demographic Health and Surveillance site in Matlab.[6] The Ministry of Health and Family Welfare of Bangladesh is developing a national cholera control plan aimed at making substantial reductions in cholera morbidity and mortality in the decade. Most patients with acute watery diarrhoea are not systematically tested for cholera, and there is no systematic reporting of suspected cholera nationally, leaving decision makers with few datapoints to devise plans or to monitor progress
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