West Nile Virus

The following Halton Catholic District School Board West Nile virus information sheet has been developed in consultation with the Halton Regional Health Department.

General information

  • West Nile virus (WNV) is a virus that is found in wild birds (e.g. crows, blue jays) and spread by mosquitoes.  Mosquitoes get the virus by feeding on the blood of an infected bird.  West Nile virus is transmitted to humans through the bite of an infected mosquito.
  • In Halton Region the season for mosquitoes, depending on warm weather conditions, is from May to October.
    West Nile virus is not transmitted through casual person to person contact, or through contact with animals (e.g. birds or horses).
  • Mosquitoes are attracted to humans for many reasons, some being: chance for a blood meal, carbon dioxide from breath, skin odours, body heat, cologne, perfumes, scented body lotions and dark clothing.
    People of all ages can be infected with WNV and some will have severe illness.
  • Of those infected, the majority (80%) will have no symptoms; a low proportion will develop West Nile fever, which consists of fever, headache, muscle ache, and skin rash.  In a small percentage of West Nile fever patients these symptoms may progress to the more serious illnesses involving inflammation of the brain (encephalitis) and spinal cord (meningitis) and, at times, death. 
  • Parents or caregivers should contact a doctor immediately if a child develops symptoms such as high fever, confusion, muscle weakness, severe headaches, stiff neck, or if his or her eyes become sensitive to light.
  • There is no specific treatment or vaccine against West Nile virus at this time. The symptoms and
    complications can be treated.

Student and the school day - frequently asked questions

Is my child at risk for becoming infected with West Nile virus while attending school?
The mosquitoes that most commonly carry West Nile virus (Culex pipiens) are generally active during the early evening to early morning hours so children who attend school during the daytime are at minimal risk for exposure. The school yards are mainly located in open areas on asphalt or short grass/dirt – not conducive for harbouring mosquitoes. As well, the school is actively involved in reducing mosquito breeding sites (standing water) and resting sites (tall grasses and weeds) on school property. Children are at minimal risk for exposure to mosquitoes.
Can children go on outdoor field trips and play outdoors during the summer?
Children who go on field trips during the day in areas away from standing water (over 7 days), wooded, swampy areas, tall grasses and bushes are at minimal risk for exposure to mosquitoes. Where trips or activities take place from early evening (dusk) to early morning (dawn) or in areas that are wooded, shaded,  or swampy areas or with standing water (over 7 days), the students will be advised to take precautions (e.g. cover up, use insect repellent).
If a child is bitten by an infected mosquito, will he or she get sick?
Most people, including children, who are bitten by mosquitoes carrying the West Nile virus, may experience no symptoms or a very mild illness. Parents or caregivers should contact a doctor immediately if a child develops symptoms such as high fever, confusion, muscle weakness, severe headaches, stiff neck, or if his or her eyes become sensitive to light.

Precautions - personal protection - fight the bite!

  1. Avoid being outdoors, where mosquitoes are present, from early evening (dusk) to early morning (dawn). This is when the female mosquitoes are most active and likely to bite for a blood meal..
  2. Cover up.  light coloured long-sleeved shirts and long pants with a fabric thick enough to prevent mosquitoes from biting.  Socks and shoes are also recommended.
  3. Use an insect repellent. Strictly follow the manufacturer’s directions. Repellents need only be used if you are going to be outdoors during the early evening to early morning hours or when in wooded, weedy/long grass, or  swampy areas.
  4. Reduce mosquito breeding sites around your home such as removing standing water.  Mosquitoes need only an inch of standing water that has been standing for at least seven days to breed.

Health precautions if using a DEET based insect repellent

  • Carefully read and strictly follow the manufacturer’s directions.
  • Only the least concentrated product (10% DEET or less) should be used;
  • For children between 2-12 years of age a maximum of three applications per day may be used in situations where a high risk of complication from insect bites exist;
  • Do not allow young children to apply DEET products themselves;
  • Caregivers applying DEET should apply to their hands first and then put it sparingly on child’s exposed skin avoiding the child’s face and hands. Clothing may also be sprayed.  Caregiver should wash their  hands after application.  Where washing is not possible, keep your hands away from eyes and mouth.
  • Wash all treated skin and clothing after returning indoors.
  • For further information for children aged 6 months to 2 years, call your doctor or the National WNV info line at 1-800-816-7292.

DEET Facts

  • DEET (N,N-diethy-m-toluamide) does not kill mosquitoes, it repels them by making the person unattractive for feeding. (DEET is a component of an insect repellent, not a brand name.)  
  • A higher percentage of DEET in a repellent does not mean that your protection is better – just that it will last longer between applications; e.g., a product with 5% DEET provides almost 2 hours of protection from mosquito bite, 10% DEET 3 hours of protection, 20% DEET 4 hours of protection, 30% DEET 5 hours of protection.

Non DEET based insect repellent

Insect repellents other than DEET-based are available in Canada, although data on their safety is sparse.  Allergic reactions may occur in some individuals.  If you choose to use them, carefully read and follow the manufacturer’s directions.  For example:  Soybean Oil – A product containing 2% soybean oil was found to protect against mosquitoes for about 90 minutes.  Repellents containing soybean oil were recently registered in Canada, and meet all the safety standards. 
Parents interested in finding answers to:
How to protect your family from mosquito bites?
What can I do around my home to protect my family from exposure to mosquitoes?
Precautions to take when using insect repellent with DEET?
Connect to the Halton Region Health Department web site: www.halton.ca/wnv
Information was taken from the: Halton Region Health Department Web Site – www.halton.ca/wnv .
For more information about the West Nile virus please call the Halton Region Health Department, (905) 825-6000 or toll free: 1-866-4Halton (1-866-442-5866) TTY: 905-827-9833