Modes of transmission of cholera in a newly infected population on an atoll: implications for control measures.

To determine the modes of transmission in a cholera epidemic in a newly infected population on an atoll, two studies were conducted, in which persons with cholera were individually matched, by age and sex, with neighbourhood controls. Among the first recognised cases, cholera was associated with frequent (daily or weekly) consumption of raw lagoon fish that had been salted and partially dried. Vibrio cholerae was isolated from the lagoon, which was contaminated by human wastes. During the declining phase of the epidemic, cholera was associated with consumption of raw clams, salt-fish, sardines, and other fish from the lagoon. When seafood from enclosed bodies of faecally contaminated water is frequently eaten raw, imported V. cholerae can become established and can be extremely difficult to eradicate.