[Isolation of Yersinia, campylobacter, Plesiomonas and Aeromonas from environmental water and fresh water fishes].

Yersinia, Campylobacter, Plesiomonas and Aeromonas are known causative agents in waterborne diseases. For about 10 years, outbreak of diarrhea has been observed, especially among children, in the mountain areas of Okayama. Y. pseudotuberculosis recently isolated from non-chlorinated drinking water sources such as mountain streams and wells has been suspected to be the causative bacteria of the disease. Attempts were made to isolate Yersinia and Campylobacter from water samples from rivers in rural areas and Plesiomonas and Aeromonas from samples of well water and fresh water fishes in Okayama prefecture from 1987 to 1990. The isolation rate of Yersinia from river water samples was 7.5% with a higher rate in the mountain areas than in the nonmountain areas. While Y. enterocolitica was isolated throughout the year, Y. pseudotuberculosis was only seen during the winter. Various serogroups including human types of Y. enterocolitica and serogroup 2B, 4A and UT of Y. pseudotuberculosis were detected. Campylobacter was isolated from 0.5% of river water samples. Plesiomonas from 1.5% of fresh water fishes, and Aeromonas was isolated from 6.9% of well water samples and 47.1% of fresh water fishes.