The Thunder Bay District Health Unit says it has reports from 55 people who became sick after eating food at catered events in the city last Thursday.

For now, the health unit is not disclosing where the events occurred, or by whom they were catered.

However, officials said the symptoms — which include vomiting, diarrhea and nausea — are typical of noro-viruses that can cause outbreaks after large gatherings where food was served.

Health Unit senior health inspector Abby Mackie said this is also the time of year when it's more likely to happen.

“It seems that we always experience an increase around the holidays,” he said.

“People are getting together — social functions, company's coming over, that kind of thing — so we do always see an increase in Norwalk-like symptoms around this time.”

Looking for a 'clearer picture'

Symptoms of the Norwalk Virus can be what Mackie calls "fairly violent" and generally last 24 to 48 hours.

Maki said the health unit wants to hear from anyone who fell ill after eating at a catered event.

For those who took some of that food home, call the Health Unit before eating it or throwing it away

"As the investigation continues, and once we know more, we can communicate it at that time,” Mackie said.

"We're trying to contact each of the attendees ... to determine what foods they ate. That will give us a clearer picture of what caused it if it was a food-borne incident.”