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Shellfish Harvesting & Control

Vibrio is a naturally occurring bacterium that inhabits coastal waters in BC.

While most incidences of shellfish poisoning occur from consuming raw oysters, exposures from recreational water contaminated with vibrio can also result in gastroenteritis and wound infections.

Spikes in vibrio 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 after eating raw BC oysters. This is the largest outbreak of vibrio in Canadian history and was 2.5 times the number of cases expected. In response to this apparent outbreak of vibrio, 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 degress Celsius above the norm. Graph of sea surface temperatures August 2014 to August 2015.


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 vibrio.

 

Vibrio control tools

A suite of tools to improve the control of vibrio have been developed over the past few years by industry experts.

Growth calculator

This calculator was developed by BCCDC as a research tool only, to estimate the potential growth of vibrio in shellfish. (Note that this tool is not a substitute for microbiological testing, which is the only accurate test for the actual growth of vibrio.)

The calculator is in a spreadsheet format. Three examples of different storage conditions are included. Users input the initial Vp load, the oyster meat temperature the time in hours that the product is maintained at that temperature. (There will be a lag time before the temperature of storage and the meat temperature are the same.) The output provided by the calculator is the estimated concentration at the end of storage.  


Sea surface temperatures map

This map shows charts of sea surface temperatures for the previous two weeks at 13 shellfish harvesting locations in BC.

Shellfish harvesting sites status map

The map shows shows the status of shellfish harvesting sites in BC: whether the site is open or closed because of contamination or for sanitary reasons.

  • Open the shellfish harvesting sites status map (page includes instructions for using the map). To view the map, wait for the map to load, then scroll to the end of the Terms of Use and click the I Accept button.

Vibrio control & shellfish harvesting management 

Shellfish harvesting process

Vibrio growth references & surveillance

SOURCE: Shellfish Harvesting & Control ( )
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