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Risk Assessment of the Public Health Impact of Vibrio parahaemolyticus in Raw Molluscan Shellfish


This risk assessment will determine the prevalence and extent of exposure of consumers to Vibrio parahaemolyticus in raw molluscan shellfish and will assess the resulting public health impact of such exposure. V. parahaemolyticus occurs naturally in the estuarine environment, and thus is present in many seafoods, including raw molluscan shellfish and other seafood.

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Investigations of outbreaks in 1997 and 1998 in the Pacific Northwest, Gulf Coast, and Northeast regions implicated this microorganism in over 700 cases of foodborne disease. The 1998 outbreak data indicate the emergence of new pathogenic strains. The risk assessment will be divided into three modules: harvest, post harvest, and public health; the public health module will be further divided into epidemiology, consumption, and dose-response. The harvest module will address regional differences and seasonal fluctuations, evaluate how environmental parameters such as temperature or salinity, influence levels in seafood in the water at time of harvest. The post harvest module will evaluate the effect of processing and handling after harvest on the levels of the microorganism in the seafood. The public health module will address the number of V.parahaemolyticus infections, the number of V. parahaemolyticus cells in the oyster at time of consumption, probability of illness with different levels of the bacteria, and the severity of illness among consumers with different immune conditions.

This risk assessment will provide the scientific framework for the development of food safety guidance and policies to reduce the risk of disease from this seafoodborne pathogen. The policy will provide guidance to the industry, State and Federal laboratories on the type of testing to be performed and what risk reduction measures need to be taken. The resulting guidance will be developed in cooperation with the Interstate Shellfish Sanitation Conference (ISSC).

Dennis, Sherri
DHHS/FDA - Center for Food Safety & Applied Nutrition
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