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Vibrio parahaemolyticus (V.p.) is a naturally occurring motile bacterium that inhabits coastal waters in BC. While most illnesses occur from consuming raw oysters, exposures from recreational water contaminated with V.p. can also result in gastroenteritis and wound infections. Seasonally, spikes in V.p. illness typically occur later in the summer months, in July, August and September. During the summer of 2015, 73 persons became ill with culture-confirmed Vibrio parahaemolyticus after eating raw BC oysters. This is the largest outbreak of V.p. in Canadian history and was 2.5 times the number of cases expected. In response to this apparent outbreak of V.p., Vancouver Coastal Health Authority banned the sale of raw oysters harvested on Vancouver Island for the first time since 1997. Among possible causes of the high number of 2015 cases was that seasonal sea temperatures during the spring and summer were, on average, 2°C above the norm.

In response to this outbreak, the industry and their association, BC Shellfish Growers’ Association, along with public health partners, regulators, and others have engaged in many different activities in an effort to improve control, education, communication and surveillance of V.p. While this work is ongoing, information and tools for Vibrio control can be found in the second tab "Tools for Vibrio Control".

Tools for Vibrio control

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.

This 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 [1]. The same formulas were used in the risk assessment conducted by the FAO and WHO in 2011 [2]. 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.

[1] 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:

[2] 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


The temperature mapping tool shows a graph of sea surface temperatures for the previous two weeks at 13 shellfish harvesting areas around BC (click on a marker to view the graph for that area).  The temperature estimates are composite values calculated based on night time observations from several satellite instruments. The temperature value represents the readings from a one kilometer square at the location marked on the chart. These data are downloaded daily and temperatures from the previous two weeks are shown on the graphs. These charts are useful to assess temperature trends and do not reflect the maximum day time temperatures, which will normally be higher than the values shown in the graphs.

tempmappingtool.PNG(source: JPL MUR MEaSUREs Project. 2015. GHRSST Level 4 MUR Global Foundation Sea Surface Temperature Analysis (v4.1). Ver. 4.1. PO.DAAC, CA, USA. Dataset accessed daily at:

If you have any questions or comments, please contact us at


Biotoxin and Sanitary Contamination Closures Map for Shellfish Harvesting in British Columbia

The BCCDC shellfish harvesting mapping tool is designed for public health officials and members of the public to view shellfish harvesting area data using a Google Maps application. Users can quickly view and search the status of shellfish harvesting areas along the coast of British Columbia. 

Please note that Fisheries and Oceans Canada is the authoritative source for biotoxin and sanitary contamination information, and users should consult with the Fisheries and Oceans Canada website for the latest information. The BCCDC has created this map to present information from Fisheries and Oceans Canada in a more user friendly manner. The map tool also includes a shellfish dictionary to describe the different species of shellfish found on the British Columbia coast.  

Launch the BCCDC shellfish mapping tool


The BCCDC shellfish harvesting mapping tool is compatible with Google Chrome, Mozilla Firefox, Microsoft Edge, Opera and Apple Safari web browsers; the mapping tool is not compatible with Internet Explorer. Some users have reported the absence of shellfish harvesting status shading (e.g. green, yellow and red shading) due to workplace firewall rules; try re-loading the webpage to resolve this issue. The map should appear as illustrated in the above image. Otherwise, please consult with your Information Technology department if you encounter technical issues.


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