Keep noroviruses at bay

Protect yourself from the viruses which cause the stomach flu.

You’ve likely heard the horror stories about people on cruise ships succumbing to noroviruses by the dozens, or hospitals struck by Norwalk. But what are these viruses and how can you prevent yourself from picking them up? Here’s an overview.

What is a norovirus?
Noroviruses are a group of viruses which cause the stomach flu. They are also a source of food poisoning in that they can be transmitted by food handlers to your food and then to you. They are part of a family called caliciviruses. One difference between noroviruses and the broader group of caliciviruses is that animals do not carry noroviruses – so you can’t get them from your pet.

The reason you may not have heard of noroviruses is that the term norovirus was only approved as the name for this group of viruses in 2002. Prior to that they were called Norwalk-like viruses.

Symptoms of infection
The symptoms of norovirus illness usually include: nausea, vomiting, diarrhea, and stomach cramps. Some people also experience 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. Most people with norovirus illness have both of these symptoms.

There is no treatment for the virus. Most healthy people will recover from a norovirus easily. The main concern is dehydration, so infected individuals should be sure to drink plenty of liquids. In young children and the elderly, dehydration is particular concern and they should be monitored.

How is it transmitted?
Noroviruses are transmitted from person to person. Noroviruses spread easily in environments where people are in close contact, including schools, day-care centres, long-term care facilities, healthcare facilities and cruise ships.

The virus is carried in the stool or the vomit of those who have the virus from as soon as they feel ill to at least 4 days after they have recovered, and sometimes up to two weeks after they have recovered. Generally people are either directly infected or infected due to surfaces contaminated with the virus, or by consuming contaminated food or water.

Noroviruses can live on hard surfaces for up to 12 hours, and some strains can live in carpet for days. However they are most commonly transmitted where people are in close contact: cruise ships, daycare centres, and healthcare facilities. They can be chlorine-resistant, requiring higher concentrations of bleach to eliminate.

Hand washing is the best defense
Noroviruses are one of the reasons that proper hand washing after going to the bathroom is important. Consider the sink, sink handles, and door handles contaminated. Use paper towels when in touch with these surfaces. Wet hands and wrists and work soap into a lather. Scrub hands for at least 15 seconds (time enough to sing “Happy Birthday”) and be sure to scrub around rings, between fingers, and under nails and around cuticles. Rinse hands thoroughly and use paper towels to dry skin. The scrubbing dislodges the virus and the rinsing carries it away.

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