Fast Determination And Risk Assessment Of Vibrio Parahemolyticus In Seafood

Vibrio parahaemolyticus is an important human pathogen in China, which could cause acute astrointestinal illness, and cause sapraemia leading to death in some cases. At present, Vibrio parahaemolyticus has become one of most serious problems which have bad effect on public health in our country. Vibrio parahaemolyticus is primary pathogen in our country ,the food poisoning caused by vibrio parahaemolyticus is going up in recent years,especially in coast areas. It is necessary to develop reliable fast method of detection and supervise contamination status of sea products with vibrio parahaemolyticus.A PCR amplification-based detection of total vibrio parahaemolyticus in seafood is developed by targeting termolabile hemolysin encode by tlh gene. The PCR is applied to detect 4 vibrio parahaemolyticus strains, 3 non-vibrio parahaemolyticus srains and 20 pieces of seafood, the result shows that the PCR approach are successfully used to detect various strains of vibrio parahaemolyticus in seafood. Sensitivity of detection for target gene segments was at least 1MPN per 100 g of alkaline peptone water enriched seeded oyster tissue homogenate. The full course of detecion coule be completed in 8 hours which is significantly shorter than the time needed by conventional techniques. Compared to conventional microbiological culture methods, this PCR approach is rapid and reliable for accomplishing a comprehensive detection of vibrio parahaemolyticus in seafood.Qingdao is a coastal city and there are many people visit here every year. The consumption of seafood is large and some consumers like eating raw or undercooked aqutic products. Vibrio parahaemolyticus is an most important human pathogen in the city, so its necessary to survey the containmination situation of sea products with vibrio parahaemolyticus in the city and take measure to ensure consumers'health. In order to get information about the vibrio parahaemolyticus contamination in retail seafoods, 326 samples are collected from seafood wholesale markets, retail markets in Qingdao city within the period from December 2005 to December 2006. The samples are determined qualitatively and quantitatively by the PCR and most probable number (MPN) technique. Incidence of vibrio parahaemolyticus in different sort of seafood ,season and area are compared. High frequency of vibrio parahaemolyticus is detected in retail seafoods. It is conclued that this pathogen needs to be intensively monitored and controlled in seafoods.An semi-quantitative risk assessment was carried out by using risk assessment software Risk Ranger. The risk of vibrio parahaemolyticus illness was predicted by risk ranger. The assessment predicts that risk rank value of vibrio parahaemolyticus illness is 52 in Qingdao, and there will be 923 case of vibrio parahaemolyticus illness due to eat seafoods every year in Qingdao. The predicted number of cases is close to real data. According to the assessment, controlling measures are suggested to ensure consumers'health, aqutic products should be put in good conditions; seafoods should be cooked enough to eliminates the pathogen and so on. The semi-quantitative risk assessment is first assessment in our country, it provides the good technical support for quantitative assessment.Through semi-quantitative risk assessment, we can obtain the risk rank value of consumers in Qingdao city. The cost of semi-quantitative risk assessment is less than quantitative assessment, but the result of quantitative risk assessment is more elaborate and comprehensive. A quantitative are undertaken to model the risk of vibrio parahaemolyticus foodborne illness associated with the consumption of raw seafoods in Qingdao city. The assessment is conducted in accordance with the widely accepted procedures and methods for risk assessment, which involves hazard identification, hazard characterization, exposure assessment and risk characterization. The outcome of the exposure assessment modules was combined with a beta-poisson dose-response model, predicting people will ingest 2-3 cell of pathogenic vibrio parahaemolyticus and the risk of illness associated with the consumption of vibrio parahaemolyticus-contaminated raw seafood to be 1.04×10-6 . The effect of control measures is evaluated by dose-response model. Implementing control measures, including reduce time unfrigerated, rapid cooling, mild heat treatment and freezing, may substantially reduce the number of illness. The quantitative risk assessment provides the good technical support for further quantitative assessment and establish standard of vibrio parahaemolyticus in seafood.