Immune responses to cholera following natural infection: a review

Cholera is an acute, diarrheal disease caused by Vibrio cholerae O1 or 139 that is associated with a high global burden. While it is accepted that natural immunity against cholera infection exists, no clear correlate of protection has been identified. In this review, we identify the estimated duration of immunity following cholera infection with and without clinical symptoms from available published studies. We searched Pubmed and Web of Science for studies examining the long-term infection-acquired immunity against cholera infection. We identified 22 eligible studies that included individuals residing primarily in Bangladesh and North America. Although with small sample sizes, three studies found that most participants with a subclinical infection from an initial challenge with cholera had a symptomatic infection when rechallenged with a homologous biotype, suggesting that a subclinical cholera infection may confer lower protection than a clinical one. We identified the longest duration of immunity recorded by observational and challenge studies to be three years, but all the serological studies showed that various potential correlates of protection became undetectable by one year.