A cholera epidemic among the Nicobarese tribe of Nancowry, Andaman, and Nicobar, India.

Cholera has not been reported from the Andaman and Nicobar Islands in India. In October 2002, an outbreak of diarrhea occurred among the Nicobarese tribe of the Nancowry group of islands. The outbreak affected 16 of the 45 inhabited villages of three islands with an attack rate of 12.8% and a case fatality ratio of 1.3%. Vibrio cholerae O1 El Tor was isolated from 18 of the 67 patients tested. A study conducted in one of the villages indicated that the outbreak was started there by a person who traveled to a nearby village where an outbreak was occurring. No specific water source could be identified as the source of infection because persons consuming water from all wells were affected. Water samples from 55 sources were tested and 38 of them were contaminated with Escherichia coli. The possible sources of V. cholerae are effluents from ships or poachers from neighboring countries where cholera is endemic.