It is essential to properly collect and store all food, in the manner recommended by the Canadian Safe Food for Canadians Act and other relevant federal, provincial, state, and local regulations, in order to reduce the risk of illness caused by food-borne pathogens. The BC Centre for Disease Control has developed this calculator as a research tool only, to estimate the growth of Vibrio parahaemolyticus (only) in shellfish. Actual growth of Vibrio parahaemolyticus or other bacteria in food should be assessed using the methods formally approved by relevant Canadian and other federal, provincial, state, and local regulations pertaining to food safety.
Vibrio parahaemolyticus growth calculator is a research tool, to be used for scientific research purposes only, designed to help the user estimate the growth of this bacteria for specific combinations of time and temperature. It provides an estimation of the potential growth of Vibrio parahaemolyticus in shellfish. Actual growth of Vibrio parahaemolyticus can only be determined accurately by microbiological testing, and this research tool cannot be a substitute for such microbiological testing. Actual growth of Vibrio parahaemolyticus will be different from the estimates provided by this calculator, (either higher or lower) depending on other factors not accounted for in this research tool. For this reason, this calculator should be used with caution, and with the full understanding that the estimates provided are only an indication of potential growth.
The calculator has been developed in a spreadsheet format and three examples of different storage conditions are included to help the users. It allows users to input the initial concentration of Vibrio parahaemolyticus, expressed in number of cells or log10, the temperature of shellfish (e.g. oyster) meat during storage in degree Celsius and the time, in hours, the product (e.g. raw oysters) is maintained at that temperature. It should be noted that there will be a lag time before the temperature of storage (or ambient temperature) and the meat temperature are the same.
The output provided by the calculator is the estimated concentration at the end of storage, which is given in log10 or in number of Vibrio parahaemolyticus cells. The formulas to estimate growth of Vibrio parahaemolyticus in this calculator are those used in the post-harvest module of the Quantitative Risk Assessment on the Impact of Public Health Pathogenic Vibrio parahaemolyticus in Raw Oysters, published in 2005 by the US Food and Drug Administration . The same formulas were used in the risk assessment conducted by the FAO and WHO in 2011 . As per these risk assessments, the formula for the growth rate includes a correction ratio of 4 to account for different rate of growth in oysters compared to broth.
 FDA [US Food and Drug Administration]. 2005. Quantitative Risk Assessment on the Public Health Impact of Pathogenic Vibrio parahaemolyticus in Raw Oysters. US Department of Health and Human Services, US Food and Drug Administration. Available at:
 FAO/WHO [Food and Agriculture Organization of the United Nations/World Health Organization]. 2011. Risk assessment of Vibrio parahaemolyticus in seafood: Interpretative summary and Technical report. Microbiological Risk Assessment Series No. 16. Rome. 193pp. Available at:
Accessed February 17, 2016