West Nile Virus

How is the virus spread?

West Nile Virus (WNV) is spread to humans by the bite of an infected mosquito. Mosquitoes become infected by biting an infected bird. The virus is not spread by person-to-person contact. It cannot be spread directly from a bird to a human. In a very small amount of people, WNV has been spread through blood transfusions, organ transplants, breastfeeding, and from mother to child during pregnancy.

The risk of becoming seriously ill as a result of infection with WNV is low, and most people who become infected experience no symptoms or have a very mild illness.

How to tell if a mosquito bite is serious:

Most mosquito bites cause itching and minor irritation. Symptoms of WNV usually appear within 2 to 14 days after being bitten. Some of the less serious symptoms are:

• fever,
• muscle weakness,
• fatigue (tiredness),
• swollen glands,
• headache, and
• rash.

More serious symptoms are rare but can occur especially in older people and in people who are immunocompromised. If you have any of the following symptoms after being bitten by a mosquito, get medical attention immediately:

• Rapid onset of severe headache
• High fever
• Stiff neck
• Nausea
• Loss of consciousness
• Confusion or drowsiness
• Paralysis

Extreme swelling or infection at the site of the mosquito bite is another reason to get medical attention.

Protect yourself and your family from mosquito bites:

• When going outdoors, use insect repellents that contain DEET or other approved ingredients.
• Wear light coloured long-sleeved shirts, long pants and a hat. Mosquitoes are attracted to dark colours.
• Stay out of wooded areas during dawn and dusk.
• Make sure that screens for doors and windows have no holes and fit tightly.

Should you use DEET-containing repellent?

Health Canada advises that DEET-containing repellents are not to be used on children under 6 months of age. DEET may be considered for children aged 6 months to 2 years if there is a high risk of infection if the child gets bitten. For these children apply once a day and use sparingly; avoid application to the face and hands. For children 2 to 12, apply DEET no more than three times a day and use the least concentrated product (10% DEET or less). For children older than 12 and adults, products containing no more than a 30% concentration of DEET will provide sufficient protection. Apply sparingly.

Keep these other tips in mind, too, when using insect repellent:

• apply repellent sparingly on exposed skin surfaces or on top of clothing,
• do not use under clothing,
• do not use repellent on open wounds, or if skin is irritated or sunburned,
• do not get in eyes; if this happens, rinse with water right away,
• wash skin with soap and water when you return indoors, or when protection is no longer needed,
• avoid breathing mist from a spray-type repellent,
• always apply in a well-ventilated area; never apply spray repellent inside a tent,
• do not use near food, and
• read the manufacturer's instructions carefully.

Make sure mosquitoes are unable to breed on your property:

Mosquitoes can lay their eggs even in small amounts of standing water. It takes about four days for the eggs to grow into adults. Health Canada recommends:

• draining standing water two times a week from items like pool covers, saucers under flower pots, recycle bins, and garbage cans,
• removing unused items (i.e., old tires) from around your property that may collect water,
• drilling holes in tire swings so water can drain out,
• changing the water in children's wading pools, bird baths, pet bowls and livestock watering tanks twice a week,
• covering rain barrels with screens, and
• cleaning out eavestroughs regularly to prevent clogs that can trap water.

If you have any questions, contact KFL&A Public Health at 613-549-1232.

Revised: 2012-10-10