Norovirus Outbreak in Canada Linked to Spot Prawns

Carolyn Crist

June 13, 2022

Sixty cases of norovirus and gastrointestinal illness have been reported in four Canadian provinces as of June 10. Spot prawns have been identified as the source, according to a public health notice.

The investigation into the outbreak is ongoing, and more information is needed to determine how the spot prawns became contaminated with norovirus. The public health notice will be updated as the investigation continues.

"Spot prawns contaminated with noroviruses may look, smell, and taste normal," a spokesperson for Health Canada told Medscape Medical News.

"Noroviruses can be transmitted by ill individuals," the spokesperson said. "Cleaning and disinfecting practices are the key to preventing further illnesses."

The public health notice was published by the Public Health Agency of Canada on June 1.

Food Recall

All of the people who became ill with norovirus and gastrointestinal illness reported having eaten spot prawns before they became sick, according to the public health notice.

On May 31 and June 2, the Canadian Food Inspection Agency issued food recall warnings for several lot codes of spot prawns that were associated with the illnesses in the investigation.

Certain Tri-Star Seafood Supply brand live spot prawns were recalled, including variable sizes under the lot codes AJ200-021, CA001-1532, CA001-1540, and CA001-1542.

The recalled products were sold in Alberta, British Columbia, Ontario, and Manitoba. They may have been distributed in other provinces and territories as well.

Among the cases identified so far, 19 were in Manitoba, 12 were in Alberta, 18 were in British Columbia, and 11 were in Ontario. People became sick between mid-May and late May, and no deaths have been reported.

Although not all cases have been tested, laboratory testing confirmed the presence of a norovirus infection in some cases, according to the public health notice.

The Canadian Food Inspection Agency is continuing its investigation, which may result in additional recalls. If other products require another recall, the agency will issue additional warnings.

"Do not eat, use, sell, or serve the recalled spot prawns," the public health notice said. "Check to see if you have the recalled spot prawns at home. If you do, throw them out and wash your hands."

Norovirus Illness

Acute gastrointestinal illnesses, including those caused by noroviruses, are common in North America and are highly contagious, according to the public health notice.

The illness can affect all age groups. However, young children, older adults, pregnant women, and people with compromised immune systems face the highest risks of developing more serious complications.

People who contract norovirus illnesses usually develop symptoms of gastroenteritis within 24-48 hours, though symptoms can start as soon as 12 hours after exposure. The illness often begins suddenly, according to the public health notice.

The main symptoms of norovirus illness are diarrhea, vomiting, nausea, and stomach cramps. Children typically have more vomiting than adults. Other symptoms may include low-grade fever, headache, chills, muscle aches, and fatigue.

Most people recover within 1 or 2 days, as symptoms resolve on their own, and don't experience long-term health effects, according to the public health notice. Patients should drink plenty of liquids to replace body fluids that were lost owing to diarrhea and vomiting.

Those who develop more serious complications may become dehydrated, and in severe cases, patients may need to be hospitalized to receive fluids intravenously. Healthcare providers should be aware of outbreaks and treat patients who appear to have severe symptoms of norovirus illness.

Consumers should follow safe food-handling practices, such as avoiding the consumption of raw or undercooked spot prawns, eating spot prawns soon after cooking, and refrigerating leftovers. People should also separate raw and cooked spot prawns to avoid cross-contamination and avoid using the same plates or utensils for raw and cooked items.

Food handlers and consumers should wash their hands thoroughly before and after handling any food and sanitize cutting boards, counters, knives, and other utensils after preparing raw foods.

In addition, consumers and healthcare providers should clean and disinfect contaminated surfaces after a norovirus illness. After vomiting or diarrhea, clothing and linens should be removed immediately and washed with soap and hot water. Those who have been diagnosed with norovirus illness or other gastrointestinal illnesses should not prepare food or pour drinks for other people while an infection is active, while symptoms are present, or during the first 48 hours after recovery.

"Safe food-handling practices will reduce your risk of getting sick," according to the public health notice. "Even after having a norovirus illness, patients can still become reinfected by norovirus."

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