July 25, 2006
West Nile virus arrived in Alberta in July 2003. It is a disease of birds that mosquitoes can also transmit to other animals. While most animals are not affected, horses and humans can become ill if infected.
In Alberta, only one mosquito species — Culex tarsalis — is known to carry West Nile virus. Most people bitten by an infected mosquito will show no symptoms, but one in five will develop West Nile Non-Neurological Syndrome (formerly known as West Nile Fever), which can result in fever, severe headache, chills and body aches, often requiring extended bed rest. A small number of individuals will experience the more severe symptoms of West Nile Neurological Syndrome.
While there was a low occurrence of West Nile virus in the province last summer, not enough is known about the virus to predict what will happen this summer. Everyone should take routine precautions against mosquito bites.
On this page:
How to avoid West Nile virus
Simple steps to avoid mosquito bites can help keep you from contracting West Nile virus:
- Use a mosquito repellent containing DEET on exposed skin and over clothing. DEET is recommended because it is the most effective insect repellant when used according to instructions. See Health Canada's "Safety Tips on Using Personal Insect Repellents."
- Place mosquito netting over infant carriers.
- Wear long-sleeved shirts and pants when outside at dawn and dusk when mosquitoes are most active, or avoid outdoor activities at these times.
- Make sure that door and window screens fit tightly and are free of holes to keep mosquitoes out of your house.
Reduce mosquito numbers near you
Mosquito eggs and larvae can develop in any standing water, even small amounts. Albertans can take some simple steps to reduce mosquito breeding grounds:
- Regularly empty places where standing water can collect around your yard, such as pool covers, flower pot saucers, children's toys, pet bowls and wading pools.
- Clean eavestroughs regularly so water does not collect.
- Empty and clean bird baths twice weekly.
- Cover rain barrel openings with mosquito screening or seal them tightly around the downspout.
- Aerate ornamental ponds or stock them with fish that eat mosquito larvae.
- Free your yard of debris, such as old tires, that can collect rainwater.
Help track West Nile virus
The province has developed a West Nile surveillance program to learn more about the virus in Alberta.
Although many bird species can be infected with West Nile, crows, magpies and jays seem to be highly susceptible to the virus and die soon after infection. A bird surveillance program is focused on these birds.
This year, the surveillance program will be limited to the area east of Highway 2 and south of Highway 12. If you find a fresh dead crow, magpie, jay or raven in this area, place it in a plastic bag and drop it off at any Fish and Wildlife office throughout the province. When moving any "found dead" wildlife, always wear gloves, pick up the carcass using a bag inverted over your hand, or use a stick to move the dead animal into a container. If bird carcasses can't be brought in right away, they can be placed in a freezer. For information about the Fish and Wildlife office nearest to you, call 310-0000.
The surveillance program will be discontinued once six birds from this area have tested positive for West Nile virus.
In addition to the bird surveillance, the province will also monitor mosquitoes. Surveillance centres in southern and central Alberta will trap and submit mosquitoes for testing. Trapping will increase if the virus becomes active.
Ongoing updates of the number of cases found in birds, horses, mosquito pools and humans across the province are available online.
Symptoms of West Nile virus
One in five people infected with the virus can develop symptoms of West Nile Non-Neurological Syndrome (formerly known as West Nile Fever), including:
- fever
- severe headache
- chills and body aches
In rare cases, the virus can lead to West Nile Neurological Syndrome. Symptoms can include:
- high fever
- worsening headache and neck stiffness
- coma and tremors
- convulsions
- paralysis
- muscle weakness
- numbness or difficulty moving
Long-term neurological effects have occurred in about 50 per cent of cases of West Nile Neurological Syndrome. In rare cases, a West Nile virus infection can be fatal.
You should contact your doctor if you notice these symptoms. There is currently no human vaccine against the virus.
Livestock/animal vulnerability
The West Nile virus can also affect horses. Owners are advised to consult their veterinarian for more information about the vaccine that is available for horses. As well, they are encouraged to take precautions to reduce mosquito exposure, such as smudges and sprays, and keeping horses in a barn at night.
Illness due to West Nile has not been found among sheep, pigs or cattle. Illness in otherwise healthy dogs and cats is rare.
West Nile virus does not spread from horse to horse, or person to person.
Mosquito control
The provincial government is providing municipalities in high-risk areas with funding to help control Culex tarsalis mosquitoes. The funding is based on evidence of the virus in birds, humans and mosquitoes over the last two years, as well as the natural regions of the province.
|
