Establishment and Application of Risk Assessment Model of Vibrio parahaemolyticus in Oyster Culture Course Through Analytic Hierarchy Processing

Abstract：Vibrio parahaemolyticus (VP) is a pathogen that is the leading cause of shellfish-associated cases of bacterial food poisoning.V.parahaemolyticus,detectable in both human and fish,has higher densities in oyster and other filter-feeding shellfish than in human.Raw and undercooked oyster is one of the most important ways of V.parahaemolyticus infection,thus reducing the number of V.parahaemolyticus in oysters is essential to the safety of consumers.To assessment the risk of V.parahaemolyticus outbreak during oysters culture,the risk assessment framework of V.parahaemolyticus was established by using expert experience knowledge and modern mathematics method,which consisted of risk evaluating index system,analytic hierarchy process (AHP),and multiple objective comprehensive evaluation (MOCE).It was confirmed that 3 primary risk factors (water quality,cultivation and physical condition) and 13 secondary risk factors (water temperature,salinity,pH,ammonia,nitrite,dissolved oxygen,breeding mode,density,site selection,daily management,bacteria,parasites,viruses) determined the risk caused by V.parahaemolyticus.Risk assessment model of V.parahaemolyticus during oyster culture was constructed by analytic hierarchy processing.The weights of 3 primary risk factors were 0.5278,0.3325,and 0.1396.The top three index weight were water temperature (0.2270),salinity (0.1368) and stocking density (0.1409).The risk degree of V.parahaemolyticus was determined by appropriate threshold.Then,it was preliminarily validated by studying the case of one oyster farm in Yangjiang,Guangdong with methods of multiple objective comprehensive evaluation,the risk value of V.parahaemolyticus outbreak in spring,summer,autumn and winter,respectively,was 0.2281,0.5833,0.2723 and 0.1347,respectively.The model was able to assess the risk of V.parahaemolyticus in oyster farming.