West Nile Virus (WNV) is an infection that is usually spread to humans by mosquitoes. (Affected mosquitoes have fed from the blood of birds that are infected by the virus.) In 2002, scientists discovered that people could be infected with West Nile virus in other ways, including blood transfusions and organ/tissue transplants. Recent evidence suggests that pregnant women can pass the virus to their unborn babies and that the virus may be passed through breast milk. It has also been discovered that laboratory workers who handle infected specimens can contract WNV through needle punctures or cuts.
The risk of contracting the disease from any means is considered very low, with mosquito bites being by far the most common. However, even in areas where mosquitoes do carry the virus, less than one percent of mosquitoes are actually infected. If a person is bitten by a mosquito carrying the virus, the chance of developing a serious illness from the bite is lower than one percent.
Most people infected with WNV either show no symptoms at all or have mild flu-like symptoms lasting a week or less. A rash is also a common symptom of infection. However, in rare cases, WNV may cause meningitis (inflammation of the lining of the brain and spinal cord) or encephalitis (inflammation of the brain itself). Both these diseases can cause serious debilitation. The very young, the elderly, and those with suppressed immune systems are most at risk for severe symptoms of WNV.
To help protect you and your family from WNV, London Drugs has recently produced an informative brochure, What You Should Know About West Nile Virus. You will find this in the pharmacy department.
Although there have been a few cases of WNV in humans in the prairie provinces and British Columbia, the majority of cases have, so far, been recorded in Ontario.
In Canada, the mosquito season typically lasts from May until hard frost (late September-October) so protective activities should begin now. To protect you and your family from mosquito bites:
- Reduce outdoor activities at dusk and dawn when mosquitoes are most active.
- Wear baggy, long-sleeved shirts and pants. Make sure that you also wear socks if you plan on being outside at dusk or dawn.
- Wear light-coloured clothing since dark colours attract mosquitoes.
- Use mosquito repellents that contain DEET. The percentage of DEET in repellents should not exceed 30 percent for adults or 10 percent for children. DEET should not be used on children under six months of age. Ensure you read the instructions before application.
- Install screens on doors and windows.
- Make sure your lawn is mowed to decrease the area where mosquitoes can rest during the hot part of the day.
- Avoid or protect yourself in or near woodland, forests, salt marshes and coastal rock pools and any other places where mosquitoes may bite during the day.
Objects that hold water are potential sites for mosquitoes to develop from eggs into adults. To reduce common mosquito breeding sites around your home:
- Empty saucers under flower pots.
- Change water in bird baths and pet water/food dishes regularly.
- Empty wading pools when not in use; drain tarps, pool covers and trampolines that fill with rainwater.
- Unclog rain gutters.
- Use fine mesh to cover rain barrels and containers that cannot be dumped.
- Remove used tires and other debris where rainwater may collect.
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