Survival of Kanagawa-positive strains of Vibrio parahaemolyticus in a brackish-water area.

Vibrio parahaemolyticus was observed to overwinter in sediments and to be present in considerable numbers in sediments and Clithon retropictus (gastropod mollusc) during summer months at a brackish-water area along Hashizu Creek in Japan. The highest level of the organisms was 9.3 X 10(6) and 2.3 X 10(7)/100 g in sediments and C. retropictus respectively. Production of Kanagawa haemolysin was detected in approximately 12% and 20% of strains isolated from sediments and C. retropictus respectively at two stations in Hashizu Creek but were not detected at the other three stations. Two haemolysin-producing strains were isolated from water samples but none were isolated from Corbicula japonica (bivalve mollusc). These findings suggest that haemolysin producers are preserved principally in sediments and some shellfish in the brackish-water areas with restricted salinity conditions.