Surveys on the Contamination of Marine Fish with Non-O1 Vibrio cholerae and Vibrio mimicus and Food Poisoning Cases by These Organisms

The present paper describes the relationship between the contamination with non-O1 Vibrio cholerae and Vibrio mimicus of marine fish, with special reference to the seasonal variation and the concentration of contamination, and the actual cases of domestic food poisoning by these organisms. A 10 year survey revealed that non-O1 Vibrio cholerae (non-O1 V. cholerae)strains were frequently isolated from fish during the summer season with some variations from one year to another, and isolates from fish showed similar biological properties to those of isolates from diarrhea cases of over-sea travellers. Experimentally enteropathogenic strains were included among these isolates.Vibrio mimicus (V. mimicus) strains were also isolated from fish, the frequency being not so high as in strains were also isolated from fish, the frequency being not so high as in V. choleraeStrains of serovar o-41 which was most predominant among strains from diarrhea cases were also detected among the isolates from fish. The viable cell counts, however, were very small with regard to both non-O1 V. cholerae and V. mimicus From these observations, factors causing food poisoning by non-O1 V. cholerae or V. mimicus seemed to be essentially similar to those by Vibrio parahaemolyticus (V. parahaemolyticus) ;that is, the food poisoning by non-O1 V. cholerae or V. mimicusis apt to occur in the summer season and is caused by the consumption of raw fish, although the frequency might be significantly low in comparison to that of V. parahaemolyticus.The actual cases of the domestic food poisoning by non-O1 V. cholerae or V. mimicus were retrospectively surveyed by the literature. At least 10 cases have been disclosed, among which 4 were caused by non-O1 V. cholerae and 6 by V. mimicus. Nine out of 10 cases occurred during the period from the end of July to the end of September. In most cases in which the causative foods were known, the consumption of raw fish seemed to be related. Although the serovars were different, all of the non-O1 V. cholerae strains from food poisoning cases showed similar biological properties to those from fish, being capable of growing on TCBS agar plate in which colistin was added at the final concentration of 1 pg/ml and unable to or lately ferment cellobiose. Five out of 6 cases by V. mimicus mimicus seemed to reflect the ecology of these organisms in fish.