Vibrio cholerae serogroup O139: isolation from cholera patients and asymptomatic household family members in Bangladesh between 2013 and 2014

BACKGROUND: Cholera is endemic in Bangladesh, with outbreaks reported annually. Currently, the majority of epidemic cholera reported globally is El Tor biotype Vibrio cholerae isolates of the serogroup O1. However, in Bangladesh, outbreaks attributed to V. cholerae serogroup O139 isolates, which fall within the same phylogenetic lineage as the O1 serogroup isolates, were seen between 1992 and 1993 and in 2002 to 2005. Since then, V. cholerae serogroup O139 has only been sporadically isolated in Bangladesh and is now rarely isolated elsewhere. METHODS: Here, we present case histories of four cholera patients infected with V. cholerae serogroup O139 in 2013 and 2014 in Bangladesh. We comprehensively typed these isolates using conventional approaches, as well as by whole genome sequencing. Phenotypic typing and PCR confirmed all four isolates belonging to the O139 serogroup. FINDINGS: Whole genome sequencing revealed that three of the isolates were phylogenetically closely related to previously sequenced El Tor biotype, pandemic 7, toxigenic V. cholerae O139 isolates originating from Bangladesh and elsewhere. The fourth isolate was a non-toxigenic V. cholerae that, by conventional approaches, typed as O139 serogroup but was genetically divergent from previously sequenced pandemic 7 V. cholerae lineages belonging to the O139 or O1 serogroups. CONCLUSION: These results suggest that previously observed lineages of V. cholerae O139 persist in Bangladesh and can cause clinical disease and that a novel disease-causing non-toxigenic O139 isolate also occurs.This study was supported by a Grant OPP50419 from the Bill & Melinda Gates Foundation and National Institutes of Health (U01A1077883, R01AI106878 and U01AI058935). Additionally, the study was supported by the core grants of icddr,b. icddr,b is thankful to the Governments of Australia, Bangladesh, Canada, Sweden and the UK for providing core/unrestricted support. AEM and NRT were supported by Wellcome Trust grant 098051. AEM is supported by Biotechnology and Biological Sciences Research Council grant BB/M014088/1. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.This is the final version of the article. It first appeared from PLOS via http://dx.doi.org/10.1371/journal.pntd.000418