West Nile Virus - What You Should Know

The unnerving drone of a mosquito is a familiar refrain for many Canadians. What used to be nothing more than an irritant, and an effective sleep disruption, is increasingly becoming a serious threat to both our health and our environment.

Last year, more than 1 300 Canadians became ill after being infected with West Nile virus – a 200 per cent increase from 2002. There are no indications that infection rates will subside this year.

Evidence shows that most people are infected with West Nile from the bite of an infected mosquito. A mosquito becomes a carrier of the virus when it feeds on the blood of a bird that is infected. The mosquito can also pass the virus to other animals through its bite.

As with other blood-borne viruses, there is evidence that West Nile can be transmitted through the human population by transfusions and organ/tissue transplants, though the risk of contracting West Nile virus this way is considered to be quite low. There is also evidence that West Nile virus can be passed through breast milk and from a mother to her unborn child.

Symptoms of West Nile Virus

Health Canada studies indicate that most people who contract West Nile virus have mild symptoms, or no symptoms at all. When infection does cause illness, symptoms will typically appear within two to 15 days. In mild cases, there may be flu-like symptoms, including fever, headache and body aches. Some people may also develop a mild rash, or swollen lymph glands.

Some people exhibit severe responses to the virus, which can result in the development of potentially fatal conditions such as meningitis, encephalitis and acute flaccid paralysis.

Infants, the elderly, people with weaker immune systems and people with chronic diseases are at greater risk for serious health effects. However, individuals of any age or health status can develop critical health effects associated with West Nile virus infection. Everyone should take precaution to avoid mosquito bites.

An Ounce of Prevention

The best way to protect yourself and your family is by minimizing your exposure to mosquitoes and by eliminating mosquito breeding grounds around your home and vacation property.

There are simple actions you can take to greatly reduce your risk of contracting West Nile virus.

• Try to avoid spending time outdoors when you notice that mosquitoes are most active;
• Use insect repellents that contain DEET;
• Wear protective clothing such as long-sleeved shirts, long pants and a hat. Light-coloured clothing is best, as mosquitoes are attracted to dark colours;
• Ensure that door and window screens fit tightly and have no holes that may allow mosquitoes indoors.

Handling the Threat

Effective control of West Nile virus will require the cooperation and participation of local, municipal, provincial/territorial and federal agencies, community organizations, and the Canadian public.

In February 2000, the West Nile Virus National Steering Committee was created to develop a coordinated approach to respond to West Nile virus in Canada. The committee is chaired by representatives from Health Canada, and its members include representatives from the Department of National Defence, Environment Canada, Parks Canada, the Canadian Food Inspection Agency, the Canadian Cooperative Wildlife Health Centre and provincial Ministries of Health, Conservation, Environment and Natural Resources. Health Canada also works in collaboration with blood operators and other interested organizations across the country.