Detection of toxigenic Vibrio cholerae in a traveler with diarrhea lacking classic features, returning from Delhi, India.

Cholera is an infectious disease caused by Vibrio cholerae which has caused several global pandemics since 1817. Currently, Japan is not a cholera-endemic country, and only a few cases of imported disease are reported annually. Vibrio cholerae is classified into more than 200 serogroups according to the differences in the O antigen on the cell surface, and only the O1 or O139 groups that produce cholera toxins are called cholera. We report a case in which toxigenic Vibrio cholerae O1 was detected in a 64-year-old Japanese traveler returning from Delhi, India, who presented with diarrhea without rice-water stools. Multiple potential diarrheal pathogens were simultaneously detected, including Clostridioides difficile toxin A/B and pathogenic Escherichia coli (E. coli) including enteroaggregative, enteropathogenic, and enterotoxigenic E. coli, making definitive attribution of symptoms to a single pathogen difficult by Genetic testing (BioFire FilmArray Gastrointestinal Panel). This case highlights the diagnostic uncertainty that arises with multiplex PCR-based stool testing: while such panels improve detection sensitivity, distinguishing true infection from colonization remains a clinical challenge. Clinicians should integrate laboratory findings with travel history and clinical course rather than relying solely on molecular test results.