Now that the weather is warming and Canadians are starting to think about seaside vacations, trips to the beach or even just eating on a restaurant patio, some are concerned that a bacteria called vibrio could ruin a summer favorite.
If affected by vibrio, oysters — particularly raw oysters — can cause serious gastrointestinal disease. While vibrio isn’t a new threat, experts say climate change is causing it to spread, making it a growing concern.
Does that mean you should give up raw oysters for good? While some are sharing claims on social media that vibrio can cause necrosis and even death, food safety experts like Dave Love say the truth isn’t so scary, but people should still be careful.
Love, a senior scientist at the Johns Hopkins Center for a Livable Future, says Canadians need to weigh certain risks when it comes to eating raw fish.
So if you’re hoping to enjoy shellfish in the coming months, here are some tips on how to do it safely and what to look out for.
What is Vibration?
Vibrio are naturally occurring bacteria that live in the sea. There are several, but the one most commonly mentioned when talking about crustaceans and foodborne illnesses is vibrio parahaemolyticus.
While this form of vibrio has been around forever, Love says it grows in warm water, and as climate change causes water temperatures to rise, so does the amount of vibrio.
“It’s also increasing where Vibrio lives, geographically,” he said. “So vibrio is now spreading to parts of the world that haven’t seen vibrio before.”
Oysters are part of a group of animals called filter feeders. They feed by squeezing plankton out of the water, but their filters can also trap algae and bacteria.
“They collect food, but also vibrio,” Love said. Although clams and mussels are also filter feeders, the focus is often on oysters, as they are usually eaten raw.
Information morning – NS10:27Warming oceans push an oyster-dwelling bacertia north
New research shows that warming ocean temperatures are driving something called “vibrio bacteria” farther north, exposing shellfish consumers to sometimes deadly diseases. Charles Purdy runs Bay Enterprises. Tom Smith is Executive Director
What is Vibriosis?
Eating raw or undercooked shellfish that contain vibrio can cause an infection called vibriosis, according to Health Canada.
It is usually a foodborne illness, but it can also result from exposing an open wound to vibrio-contaminated water.
According to Health Canada, you can become infected by:
- eating raw or undercooked shellfish, especially oysters.
- drinking contaminated water.
- exposing open wounds to salt water or brackish water (where fresh and salt water meet), raw seafood, or seafood juices.
- fishing in marine coastal waters and estuaries.
- peel oysters.
Symptoms often appear 24 hours after exposure and can include diarrhea, abdominal cramps, nausea, vomiting, and headache.
“Most people would think of it as food poisoning,” Love explains, nothing that while symptoms can last for up to seven days, most cases clear up on their own.
How do I avoid getting sick?
“It’s impossible to see vibriobacteria with the naked eye,” Love said.
According to Health Canada, foods containing vibriosis may even smell and taste normal, so the key to avoiding it lies in knowing where the seafood comes from and how it’s prepared.
Love suggests cooking oysters over high heat, by frying, roasting, or baking them. And when you buy oysters, whether from a restaurant or a store, he says, you should ask to see the label on the bag.
“Every bag of oysters should have a label showing where it was harvested and the date it was harvested,” he said. “That way you know that it has been harvested in a safe and responsible way.”
Love notes that seafood should be refrigerated right away and kept in the refrigerator until ready to eat. He recommends eating raw oysters for no longer than seven to 10 days from the date they were harvested.
Is Eating Raw Oysters Safe?
According to Love, eating raw oysters is much riskier than eating cooked oysters, but that goes for any meat.
Despite the potential for disease, Love says the risks are still relatively small.
“In the summer, the risk is highest that one in 10,000 raw oysters is eaten.”
However, Health Canada recommends that people who are more at risk for complications should avoid raw or undercooked shellfish altogether. This also applies to pregnant women, the elderly, children and people with a weakened immune system, liver disease or low stomach acidity.
