Since we last reported on the ongoing outbreak of norovirus and gastrointestinal illnesses linked to raw and undercooked oysters from British Columbia in mid-February, the number of outbreak cases have risen by 100, according to The Public Health Agency of Canada Tuesday.


As of March 27, a total of 321 clinical cases of gastrointestinal illness linked to oysters have been reported in three provinces: British Columbia (223), Alberta (42), and Ontario (56). No deaths have been reported. Individuals became sick between December 2016 and March 2017. All individuals who became ill reported having eaten oysters.

The source of illness has been identified as oysters from British Columbia but the cause of the contamination has not been identified. The outbreak is ongoing with illnesses linked to raw and undercooked oysters continuing to be reported, indicating contaminated oysters remain on the market (including restaurants, seafood markets and grocery stores). There continues to be a risk of norovirus infection and gastrointestinal illness associated with the consumption of these oysters.

Although not all cases of illness have been tested, testing of several cases has confirmed the presence of norovirus infection. It is suspected that norovirus illness, caused by consumption of contaminated oysters, is the cause of illness in the untested cases.

Norovirus is a highly contagious viral illness that often goes by other names, such as viral gastroenteritisstomach flu, and food poisoning.

The symptoms include nausea,vomiting, diarrhea, and some stomach cramping. Sometimes people additionally have a low-grade fever,chills,headache, muscle aches, and a general sense of tiredness. The illness often begins suddenly, and the infected person may feel very sick. In most people, the illness is self-limiting with symptoms lasting for about 1 or 2 days.

In general, children experience more vomiting than adults do.

Norovirus is spread person to person particularly in crowded, closed places. Norovirus is typically spread through contaminated food and water, touching surfaces or objects contaminated with norovirus and then putting your hand or fingers in your mouth and close contact with someone who is vomiting or has diarrhea.