What is Norovirus and how can I avoid it?


Norovirus Quick Facts

Norovirus is spread through contact with people who already have the illness, or through food or water that has been contaminated.

Norovirus is caused by a virus, not bacteria. Antibiotic treatments are therefore ineffective.

Wash hands thoroughly with soap and water after using the washroom and before and after preparing food

If you think you have norovirus, DO NOT prepare food for other people

Drink plenty of fluids, particularly those that will restore nutrients, and avoid caffeine and alcohol which can both have a diuretic effect.


Early last week, news broke of the spread of suspected, and later confirmed, Norovirus at a residence hall at Humber College in Toronto. By Monday, the virus had infected more than 200 people but was suspected to have nearly run its course. Students who had contracted the illness were encouraged not to return to campus or to classes until they had been without symptoms for 48 hours.

Norovirus is an illness that typically spreads quickly around hospitals, cruise ships, nursing homes, and other places where people are packed tightly together. It is a group of viruses that cause gastroenteritis and is typically the cause of diarrhea and vomiting during the winter months. Typical symptoms include nausea, vomiting, diarrhea, and stomach cramps, says Health Canada. Other symptoms may include headache, low-grade fever, chills, and fatigue.

“The illness often begins suddenly, and the infected person may feel very sick with frequent vomiting and/or diarrhea. Most people feel better within one or two days, with symptoms resolving on their own and no long-term health effects occurring after illness,“ says Health Canada.

So, how does Norovirus spread? Through contact with other people. The virus is contained in the stool and vomit of those infected with the virus.

“People can become infected with the virus in several ways,” says Health Canada on their website, “including through direct contact with another infected person; touching surfaces or objects contaminated with norovirus; or eating food or drinking water that has been contaminated.”

Food can become contaminated with the virus if the person preparing or serving it has not properly washed their hands, or through communal serving stations, such as salad bars or self-serve areas, where many people with uncertain hand hygiene may have come into contact with the food.  Humber will undergo a thorough cleaning and shut down of all self-serve food service areas in response to the outbreak.

“Most food-borne outbreaks of norovirus illness likely occur when food is contaminated by food handlers who have the virus, especially if they do not wash their hands properly after using the bathroom…Waterborne outbreaks are often caused by sewage contamination of drinking water (for example, from wells) or recreational water.”

While the virus now seems to be contained and students who were infected are on the mend, the risk of a Norovirus in a similar setting is always possible. Only days after the announcement of the outbreak at Humber, CTV News reported that over 60 children at several childcare centres in Waterloo had come down with the illness. The illness is most dangerous in the very young, the elderly, and people with weakened immune systems. 570 News reported an illness developing with symptoms consistent with Norovirus at Conestoga College in Cambridge over the weekend.

The most effective way to prevent the illness from spreading, says the Public Health Agency of Canada, is practicing proper hygiene. Wash hands thoroughly with warm water and soap after using the washroom and before and after preparing food. The Public Health Agency also recommends thoroughly washing fruits and vegetables before preparing meals and keeping raw food away from other foods when shopping or storing the items.

Health Canada also says that when preparing and handling food in the kitchen, in particular raw meat and fish, you should “thoroughly clean and sanitize all surfaces used for food preparation with a kitchen sanitizer (following the directions on the container) or use a bleach solution (add 5 ml household bleach to 750ml of water), and rinse with water.”

When caring for someone with the illness, remember to wash your hands thoroughly,  and dispose of any linens, towels and clothing that may have come in contact with the virus. Caregivers should also be sure to clean surfaces that might have become contaminated with vomit or feces from an infected person, first using hot soapy water, and afterward by disinfecting with a bleach solution.

If you suspect that you may have become infected with the virus, the Public Health Agency of Canada recommends drinking plenty of fluids. A norovirus diagnosis is reached by testing a stool sample from an infected person and treatment options for the virus are minimal, as antibiotic treatments don’t work on viruses. Most cases will resolve themselves in about 48 hours. The greatest risk to patients is of dehydration.

Dehydration symptoms, says the Public Health Agency, include “a decrease in urination, a dry mouth and throat and dizziness upon standing. A dehydrated child may cry with few or no tears and be unusually sleepy or fussy. Severe dehydration can be serious and the ill person may require re-hydration in a hospital.”

The Center for Disease Control in the US reports that each year Norovirus causes around 20 million illnesses resulting in up to 70,000 hospitalizations and between 570 and 800 deaths. Having Norovirus once does not mean you will become immune to it in the future.

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