An Ecological Study of Vibrio Parahaemolyticus

Pursuing of Fish Contamination in the Course of Fish Marketing

Abstract

The status of fish-borne Vibrio parahaemolyticus (V. P.) in the course of fish marketing in Miyazakicity and Nobeoka city, Miyazaki prefecture, from its landing through wholesale fishmarket to retailer shop, and the possibility of its secondary contaminations to other foodstuffs were investigated at the following four periods: two in hot season July and Sept., 1965, two in cold season-Nov., 1965 and Feb., 1966.
The items subjected to V. P. culture were as follows:
1) At the time of landing-the surface of fish of some given lots, water from fish-storage tanks of the fishing boats, some amount of sea-water and the mud of sea-bed at the pier.
2) At the wholesale fish-market-the surface of the fish, waste water, and the case-boxes belonging to the same lots as mentioned in 1).
3) At the retailer's-the surface of the fish of the same lots as above, knives, chopping boards, fishcontainers, refrigerators, and dish towels.
The results obtained were as follows:
1) No V. P. could be detected from any materials in Nov. and Feb. This would be compartible with the facts that no food poisoning due to V. P. ever took place in winter time, and no V.P. were found from the stool of diarrheal patients in that season.
2) To the contrary, 3 strains, 1 from fish and 2 from its surroundings were isolated in June. Thirty eight strains, 35 from fish and 3 from surroundings, in Sept.; A sharp increase of the incidence in late summer was impressive
3) Contaminations of V P. to the surroundings were observed in a few incidence in September. However, observations due to V. P. colony counting showed that the multiplication of V. P. of serologically identical type never took place at any stage of fish circulation.4) Only one strain among those isolated in this experiment was positive for the hemolysis test. And none of them coincided serologically with the strains isolated from the patients of food poisoning in 1965. About 80% of them were untypable unlike that almost all strains derived from patients were proved to be typable. These facts are suggestive of rare incidence of pathogenic V. P. in the natural world.
5) It is inconceivable that under the usual cold-chain system in this prefecture, the cause of food poisoning due to V. P. shculd occur in the course of fish circulaton from its landing to fish retailer's