An outbreak of dysentery caused by Shigella dysenteriae type 1 on a coral island in the Bay of Bengal.

An epidemic of severe dysentery occurred on St. Martin Island in the Bay of Bengal at a time when the island, with a population of 1,318, was isolated from the mainland because of the monsoon season. There were 434 cases and 28 deaths within a three-month period. Mortality (2%) was limited to the very young and the elderly. Shigella dysenteriae type 1 (Shiga bacillus) was isolated from 12 of 65 rectal swab specimens. All strains gave similar biochemical reactions and were resistant to tetracycline, chloramphenicol, streptomycin, and the sulfonamides but were sensitive to ampicillin, kanamycin, and gentamicin. No other organism was implicated in the outbreak. The disease disappeared from the island after institution of chlorination of the sources of drinking water and effective treatment of patients.