Semi-quantitative risk assessment of the contamination of Vibrio parahaemolyticus in oysters from Jinshan District, Shanghai

ObjectiveTo investigate the prevalence of Vibrio parahaemolyticus(VP)in oysters in Jinshan District, Shanghai and make assessment on the risks that may cause, providing the basis for prevention and control of foodborne disease.

MethodsRaw oyster samples with shells were randomly collected from markets, supermarkets and restaurants in Jinshan District from July to October in 2017. The content of VP in oysters was tested in accordance with the national standard methods. The semi-quantitative risk assessment for VP in oysters was made by Risk Ranger combining with the monitoring results of diet and health status of residents in Jinshan District of Shanghai in 2012-2013.

ResultsThe overall positive rate of VP in the 40 oyster samples was 80.0%(32/40). The positive rate of VP in oyster samples from farmer's markets was the highest, 85.7%(12/14), followed by those from restaurants and supermarkets. The relative risk for VP in raw oysters was 63. The probability of illness caused by VP in oysters per day per consumer of interest was 6.85×10^-4, and the total predicted patients annual incidence rate in this population was 1 247.8/10⁵.

ConclusionThe contamination of VP in seafood oysters in Jinshan District is serious. Eating raw oysters is at high risk; consumers are advised to reduce or avoid eating raw oysters, and processing food before eating is an effective method to decrease VP infection. Strengthening surveillance and management is imperative in this regard.