Alberta Health Services (AHS) says nine cases of gastro-intestinal illness — seven in Edmonton and two in Calgary — are potentially connected to people eating raw oysters from British Columbia.
AHS said Monday it was investigating the possible connection and was warning Albertans to ensure shellfish is properly cooked.
“The cluster of gastro-intestinal illnesses currently under investigation experienced onset of symptoms between March 15 and 31,” AHS said in a news release.
The health agency said the type of illness involved in these nine cases has not been lab-confirmed.
“This is the second outbreak investigation into illness linked to consumption of raw oysters, in Alberta, in the past two years. In 2017, a similar outbreak was declared and Alberta completed an investigation that confirmed 42 cases in the province were linked to consumption of raw oysters.”
Raw or “lightly cooked” oysters may contain norovirus, AHS said in a news release.
“Oysters need to be cooked to an internal temperature of 90 C for a minimum of 90 seconds in order to kill norovirus,” AHS explained.
Any oysters that didn’t open during the cooking process should be thrown out. Leftover oysters need to be refrigerated. Raw and cooked oysters should be stored separately to prevent cross-contamination.
Utensils and surfaces that touch raw oysters should be washed with soap and warm water after contacting shellfish. Hands should be washed with soap and warm water.
For more information on shellfish food safety, click here.
Consuming raw oysters or shellfish contaminated with viruses or bacteria can cause vomiting, watery diarrhea and stomach cramps. Other symptoms can include nausea, fever, headache and bloody stools.
Anyone can become ill, but people with weakened immune systems are at higher risk of developing complications.
Symptoms usually last between one day to a week and usually don’t require any treatment, AHS said. However, if symptoms persist longer or become more severe, that person should go to the doctor.
Anyone who develops symptoms within 10 to 50 hours after eating raw shellfish should call Health Link at 811.
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