Norovirus Outbreak on Toronto College Campus Appears Contained

A nasty outbreak of norovirus on a Toronto college campus appears to have run its course after sickening more than 200 students with vomiting and diarrhea over the past week. Humber College in Toronto, Canada reported that an aggressive regimen of “enhanced environmental cleaning in the North Campus student residence and common areas across campus” paired with student-oriented education about handwashing and sanitizing appears to have kept the spread of the virus in check.

Norovirus is particularly virulent in “closed places” such as daycare centers, nursing homes, and schools (although there is some dispute about patient-to-patient spread in clinical settings) and so there was great concern about the virus spreading unchecked through student residences, in particular. However, Andrew Leopold, communications director at the college, stated in reports that the number of ill students had not “increased appreciably” as of January 24, 2016, and Toronto Public Health (TPH) confirmed that although norovirus was the confirmed culprit in the outbreak, no “major increase” had been reported in the number of students ill.

At the time of publication, TPH had confirmed to local news outlets that the agency believes norovirus, not food poisoning as had been suggested at one point during the outbreak, was the culprit behind the Humber event.

Michael Finkelstein, MD, associate medical officer of health at the agency, said in reports that TPH had confirmed norovirus in two stool samples from ill students and that they would be conducting more tests over the weekend. “These laboratory results are consistent with the signs and symptoms that have been reported,” he said.

Humber College continues to encourage its students to follow “vigilant health hygiene practices” and assured students via its website that they would receive “academic consideration” if they had been ill. The college also noted in a "health issues update" that the school had thrown away all open food items from the previous week and eliminated self-serve food options for the time being. Any food that was not packaged or sealed was disposed of in hopes of containing the infection.

Centers for Disease Control and Prevention (CDC) spokesman Ian Branam observed to Contagion^® that, “Norovirus is the leading cause of illness and outbreaks from contaminated food in the United States” because infected individuals either in food services or who have contact with food that others then consume, as is common in college dining halls, often have the virus on their hands and touch various surfaces or food items that then are touched by others as well.

Aron Hall, MD, an epidemiologist at the CDC’s Division of Viral Diseases, also noted to Contagion^® that in some cases, such as during a 2008 outbreak at a Michigan College, closing areas of campus in order to clean intensively can correspond to a decline in cases.

Although a large number of students on the Humber Campus fell ill, not all were confirmed to have been infected with norovirus.

Fortunately for those who are infected, the resulting effects of the infection, though extremely unpleasant, tend to be fairly short-lived. In fact, TPH reported only a week after the first students began experiencing symptoms that most students were “feeling much better.”

It is important for previously-ill individuals to remember that norovirus often remains in their feces both before and up to two weeks after being sick, which means that individuals who are feeling healthy again can still spread the infection; this is why it is imperative that all individuals who are ill keep their hands clean and stay home until they are well for at least 48 hours.

TPH recommends that anyone experiencing norovirus symptoms “disinfect environmental surfaces with a chlorine bleach disinfectant, especially in areas that are touched often like telephones, door handles, gym equipment, or bedside rails.” The agency recommends the solution should be one-part household bleach to 50 parts water (2 teaspoons of bleach with 2 cups of water).