Detection and Quantification of Total and Pathogenic Vibrio parahaemolyticus in Anadara subcrenata in the Zhoushan Archipelago

This study aimed to investigate the prevalence of total and pathogenic Vibrio parahaemolyticus in Anadara subcrenata sampled from aquafarms and retail markets in the Zhoushan islands during June 2013 to March 2015, using the most probable number-polymerase chain reaction (MPN-PCR) method. Total V. parahaemolyticus was detected in 265 (83.86%) samples with the density 0.3 to 2400 MPN/g. In total, 30.70% and 17.41% of the samples exceeded 100 MPN/g and 1,000 MPN/g, respectively. Both highest positive rate (98.99%) and highest prevalence (median = 210.0 MPN/g) were recorded in summer. Samples from aquafarms had a higher positive rate and median than those from retail markets. Pathogenic V. parahaemolyticus was detected both in aquafarms and retail markets in all seasons but not in winter. Among the 265 tlh-positive samples, 20 (7.55%) of the samples harbored tdh, and 5 (1.89%) of the samples harbored both tdh and trh. These results indicate that the Zhoushan archipelago is severely contaminated with V. parahaemolyticus in Anadara subcrenata; these results are applicable in risk assessment and to control the risk of food-borne disease caused by V. parahaemolyticus.