Ecology and epidemiology of Vibrio parahaemolyticus on the coast of Togo.

Following the identification of V. parahaemolyticus as an important agent of choleralike gastroenteritis in Togo, studies to establish the natural reservoirs of these bacteria were performed in 1972-73. Whereas V. parahaemolyticus was rarely found in water from the Atlantic ocean, the lagoons along the coast proved to be important reservoirs. The incidence of halophilic vibrios was correlated with the salinity of these waters, which is subjected to seasonal changes with the highest sodium chloride concentration at the end of the dry season. Examination of fish and shellfish samples confirmed these results: V. parahaemolyticus was isolated from only 0.5% of freshly caught fish from the Atlantic ocean but occurred in 47.3% of fish and shellfish samples from the lagoons. A still higher occurrence was encountered in specimens purchased in the markets, with 14.3% of sea fish samples and 67.7% of specimens originating from the lagoons being positive. Since lagoons and lakes with brackish water are typical of all the coastal areas between Nigeria and Ivory Coast it is likely that V. parahaemolyticus is a widespread pathogen on the coast of West Africa.