The first 2016 case of summer food poisoning linked to the eating of raw oysters carrying Vibrio bacterium has been confirmed by the B.C. Centre for Disease Control.
It comes two weeks later than last year, when the worst outbreak on record prompted a ban on B.C. oysters. Sixty people fell ill from eating raw or undercooked B.C. oysters and another 13 from exposure to seawater with high bacteria levels.
Scientists believe the 2015 spike was caused by higher ocean temperature, and say this summer seems to be more typical.
“Every summer, we expect to see people get sick with Vibrio,” said Dr. Eleni Galanis, epidemiologist at the centre. “[This summer], it’s a later start and we’ve only seen one so far, so it’s looking more like past seasons and different from last year’s outbreak. That’s a good sign.”
The case was reported on June 30 in the Vancouver area.
Vibrio is a bacterium that grows in seawater and accumulates in such shellfish as oysters and clams. It peaks in summer months, when seawater temperatures rise.
When consumed in raw or undercooked shellfish, it can cause fever, vomiting and diarrhea.
The symptoms last up to a week and typically go away on their own, but can be treated with antibiotics.
“The only way to truly prevent this is not to consume raw shellfish. But we understand people love this product and we ask them to be aware of the risk,” she said.
Galanis said raw oysters should be kept on ice and eaten from the shell. Oysters packaged without shells are intended to be cooked and should never be eaten raw.
Steve Pocock, who owns Sawmill Bay Shellfish with his wife, Linda, near Read Island, sells an average three million oysters each year from his three farms. He estimated his business lost between $150,000 and $200,000 in sales during the six-week oyster ban last summer.
The company made up for the loss in the non-summer months, he said. And sales are up about 25 per cent from this time last year.
This year, Sawmill Bay Shellfish has increased testing for Vibrio at its farms.
“Last year, we were testing on a weekly basis. This year, we’re testing every single lot that we supply. It’s an expensive thing to do, but we feel the safety of our consumer is paramount,” Pocock said.
The company puts out between one and two lots per day.
The B.C. Shellfish Growers’ Association also launched a pilot project to monitor and track the temperature of oysters, destined for raw consumption, along the distribution chain. Oyster temperature is tracked using waterproof sensors that record it every five seconds for up to 15 days.
The association has worked with such stakeholders as the B.C. Centre for Disease Control and the Canadian Food Inspection Agency to prevent future outbreaks, said Darlene Winterburn, executive director of the growers’ association.
“We have been trying to find ways to put forward best practices, and work together to share info and ensure everyone is on the same page,” Winterburn said.
The B.C. Centre for Disease Control has also launched a Vibrio growth calculator, a temperature mapping tool and a shellfish openings-and-closures map on its website: bccdc.ca.
