A research based on the analysis of 479 coprocultures , allow the isolation of 22 strains of Aeromonas hydrophila. The epidemiological aspects, the contamination processes through water, food... and the enteropathogenic role of these Aeromonas are discussed. These bacteria seen responsible of digestive disturbances from simple gastric discomfort (nausea, light abdominal pain...) to the actual choleriform syndrome. The isolation of 7 strains from the environment (water from lagune , wells; lagune crabs) allow to suspect the role played by the seasonal variations of the lagune salinity in the development of the germ; this allow to drawn the following conclusions: the reduction of the rate of water salinity promotes the multiplication of Aeromonas and increase the risk of human contamination.