Contamination of Vibrio parahaemolyticus in Zhejiang Province and its risk assessment in shellfish

For investigating the contamination of Vibrio parahaemolyticus(V.parahaemolyticus) in Zhejiang Province and assessing the risk of it in shellfish,2 215 foods in market were collected to isolate V.parahaemolyticus with CHROMagar Vibrio agar and identify with the API 20E system.The risk assessment for V.parahaemolyticus was performed by Risk Ranger and the tdh and trh genes were detected by PCR.Results showed that the rate of V.parahaemolyticus infection was 43.06%,32.52%,22.22%,13.52%,11.44%,3.44%,2.98%,2.10%,and 2.08% in fresh sea products,raw/rare seafood,freshwater fisheries,raw meat,raw poultry,cooked meat sold in bulk,Chinese style saled,raw vegetables,and cream cake,respectively.The detection rate of V.parahaemolyticus from samples collected from August to October was much higher than that from April to June(P0.01,χ2=46.445) and the detection rate from samples collected from agricultural fairs was much higher than that from supermarkets(P0.01,χ2=10.252).The carrying rate of tdh gene reached 3.66% while no trh gene was found.The risk factors for V.parahaemolyticus infection caused by eating raw and rare shellfish were 50 and 48,respectively,and the annual infection population was 4.42×104 and 2.21×104,respectively.The risk factor would decrease to zero if food could be cooked thoroughly.These findings suggest that V.parahaemolyticus contamination of various food products in Zhejiang Province is serious.Preventing food cross-contamination,avoiding eating raw or rare seafood,and heat treatment before eating are all effective methods to decrease V.parahaemolyticus infection.