Mosquito season is here and we should make sure we know what steps we should take to protect ourselves and prepare our homes and cottages.

Today, mosquitoes are more than a nuisance. Some can carry the WNv and bites may lead to WNv infection and, in turn, mild or serious illness.

Infection may result in no symptoms, in mild illness such as 'West Nile fever', or in serious neurological illness such as encephalitis (inflammation of the brain).

Everyone is at risk, and precautions are necessary to protect yourself and your family.

Special care should be taken to ensure children are protected when they are outdoors.

If you have any of the following symptoms, seek medical help. These may be early symptoms of WNv illness, or of many other illnesses, so seek medical attention to find out the cause.

• fever
• muscle weakness
• stiff neck
• confusion
• severe headache
• sudden sensitivity to light.

Extreme swelling or infection at the site of the mosquito bite is another reason to seek medical attention. This may or may not indicate WNv infection.

If you have concerns, consult your physician.

It is impossible to tell from a mosquito bite on the skin surface whether the mosquito was carrying an infection such as WNv. Research indicates that approximately four out of five people who are bitten by an infected mosquito do not show any symptoms. While most people who become infected will experience no symptoms or will have very mild illness, for some, the symptoms will be pronounced. For a very rare few, the virus causes serious neurological illness such as encephalitis.

Your physician has the information available to determine if you need to be tested for WNv.

Since July 2003, Canadian Blood Services has had a test that screens every blood donation for West Nile virus. Giving blood is safe and it's very much needed. However, if you have donated blood and begin to feel ill after your donation, please contact Canadian Blood Services at 1-888-2-DONATE (1-888-236-6283).

• West Nile virus (WNv) is spread to humans by the bite of an infected mosquito. Mosquitoes become infected when they bite an infected bird.
• The virus is not spread by person-to-person contact through touching, coughing, sneezing, or drinking from the same cup.
• There is some evidence that a person can be infected by handling a dead bird, however, the risk is very low. Wear gloves or use a thick plastic bag if you have to handle a dead bird.
• WNv is not known to be transmitted from mammals, such as horses, to humans.

Gardners, take note. If you like to work outside, avoid early morning and evening when mosquitoes are most active unless you cover up and/or use insect repellent.

Consider using personal insect repellents that are federally registered, such as those that contain DEET (N, N-diethyl-m-toluamide). Several DEET-free botanical repellents are federally registered but provide a much shorter time of effectiveness. For minimal time outdoors (e.g., less than 30 minutes) these products provide safe, effective alternatives to DEET. Read label directions for use.

The concentration of DEET should be no greater than 30 per cent for adults and no greater than 10 per cent for children. Check the label for more detailed information or ask your pharmacist for help. Use only when needed and follow label directions carefully including restrictions for use on young children and maximum number of applications per day.

Apply repellent sparingly on exposed skin or on top of clothing. Do not use under clothing. The repellent doesn't have to be applied heavily to be effective — a light coating will do.

Everyone who is outside during the summer months gardening, golfing, walking, camping, etc., should take precautions to avoid mosquito bites.

Everyone is at risk from WNv and should make sure they use all the protection measures to avoid contact with mosquitoes.

While children are not considered to be especially at risk, we suggest that care be taken to ensure they are protected when they are outdoors, since they may not always be able to protect themselves. Use mosquito netting for babies or toddlers in cribs or strollers.

Protect yourself and your family from mosquito bites by following these simple steps :

• cover up
• use insect repellent when outdoors
• clean up all around the house and garden regularly.

Mosquitoes are attracted to darker, more intense colours so make sure you wear light colours and these types of clothing when going outside :

• long-sleeved shirts or jackets
• long pants
• tuck pants into socks for extra protection.

• The concentration of DEET should be no greater than 30 per cent for adults and no greater than 10 per cent for children. Use only when needed and follow label directions carefully including restrictions for use on young children and maximum number of applications per day.
• Choose a product that meets your specific needs. For example, if you plan to be outdoors for a short period of time, choose a product with a lower concentration of DEET (shorter protection time) and repeat only if you need a longer protection time.
• Studies have shown that products with lower concentrations of DEET are just as effective as the high concentration products, but they remain effective for shorter periods of time :
• 30% DEET provides protection for approx. 6 hrs.
• 15% DEET provides protection for approx. 5 hrs.
• 10% DEET provides protection for approx. 3 hrs.
• 5% DEET provides protection for approx. 2 hrs.
• Use only personal insect repellents that are registered in Canada. They have a registration number granted under the Pest Control Products Act and are labeled as insect repellents for use on humans.
• Never use a product labeled as an "insecticide” on your body.

• It recommends that, where there is a high risk of complications to the child from insect bites, DEET may be considered for children aged 6 months to 2 years.
• Use sparingly, avoid the face and hands, apply only once a day, and use the least concentrated product (10 per cent or less) on children aged 6 months to 2 years.
• Health Canada also advises not to apply DEET more than three times a day to children between 2 and 12 years of age.
• Always supervise the application on children. Avoid application to children's hands to reduce the chance of getting the repellent in their eyes and mouths.
• For more information, call your doctor and visit the Health Canada website for "Safety Tips on Using Personal Insect Repellents.”

When applying DEET-containing repellents to children, use sparingly, avoid the face and hands, apply only once a day, and use the least concentrated product (10 per cent or less).

• Do not use repellent on open wounds, or if skin is irritated or sunburned.
• Do not get it in your eyes — if this happens, rinse with water right away.
• Avoid breathing mist from spray-type repellent. Always apply in a well-ventilated area; never apply spray repellent inside a tent.
• Do not use near food.
• Check for sensitivity — apply repellent to a small area of skin on the arm and wait for 24 hours before use.
• Read the manufacturer's instructions on the label carefully.

The best way to keep mosquitoes away is to clean up areas where they like to breed. Unlike birds or other insects, most mosquitoes do not fly very far and tend to stay close to their breeding sites and normal habitat.

Take a look around your house and property and get rid of mosquito-friendly places that would make good breeding sites or resting places for mosquitoes.

• Clean up and empty containers of standing water such as old tires, flower pots, wheelbarrows, barrels, tin cans or small containers like bottle caps that are outdoors.
• Drill holes in the bottoms of used containers so water can't collect.
• Change water in bird baths.

• Immediately remove water that collects on pool covers.
• Make sure the pool's pump is circulating.
• Turn over wading pools when not in use.

• Don't let things pile up. Clear leaves and twigs from eavestroughs, storm and roof gutters throughout the summer.
• Make sure drainage ditches are not clogged.
• Check flat roofs frequently for standing water.

Think mosquito prevention when working in the yard. Lawn cuttings, raked leaves or other decaying debris such as apples or berries that fall from trees should be collected, recycled or mulched so that organic matter does not end up in storm sewers as a food source for mosquito larvae.

• Turn over compost frequently.
• Fill in low depressions in lawn areas.
• Clear out dense shrubbery where mosquitoes like to rest.
• Spread the word. Point out potential mosquito breeding areas to your neighbours.

• Check window and door screens for holes and make sure they fit snugly into their frames, so mosquitoes will not get indoors.
• If you don't have screens, consider sleeping under a bed net to protect yourself from mosquito bites.

For more information, the Ontario Ministry of the Environment can be contacted through the Ministry of Health and Long-Term Care's INFOline on questions regarding pesticide use for West Nile virus (WNv).

A decision to use mosquito larviciding or adulticiding follows a local risk assessment by your local medical officer of health in accordance with O. Reg. 199/03 under the Health Protection and Promotion Act.

In Canada, all pesticides are registered by Health Canada's Pest Management Regulatory Agency (PMRA). Once this agency has made a decision to register a pesticide product in Canada, the Ontario Ministry of the Environment is responsible for regulating its sale and use mainly through training, licensing and permit requirements.

Registered pesticides can be used at two different points in the life cycle of a mosquito : at the larva stage and at the adult stage.

In an effort to control mosquitoes in the larva stage, municipal larviciding programs will use pesticide products called larvicides. The larvicides will be placed in stagnant water, which is where mosquitoes prefer to lay their eggs (e.g., catch basin storm sewers).

There are a number of larvicides registered by the PMRA. However, only larvicides that have a minimal impact to the environment and do not present unacceptable risks to human health will be allowed for use by licensed applicators under an approved permit issued by the Ministry of the Environment. The public will receive advance notice before the community-based application of a larvicide. If you have concerns, you may wish to contact the local health unit to discuss your situation.

A permit is not required to larvicide on your own property if the water is wholly contained on your property with no outflow. A domestic larvicide product is now available to homeowners for limited use.

Control of adult mosquitoes involves the application of pesticides called adulticides in late evening when adult mosquitoes are most active and mosquito control is most effective. There are a number of pesticides to control adult mosquitoes registered by the PMRA.

For mosquito-borne disease control programs, Health Canada supports the use of malathion applied by ground or aerial equipment using ultra-low volume application equipment in urban areas.

Adulticides are applied by trained and licensed applicators. Advance notice must be given to the public before an adulticide is applied in a community.

The use of adulticides might be necessary among other activities when their use is indicated through the local risk assessment conducted by the medical officer of health in accordance with O.Reg. 199/03.

For more information, refer to the mosquito larviciding and adulticiding fact sheets available on the Ontario Ministry of the Environment's website.

They outline procedures that the public should know and follow in order to reduce potential exposure to pesticides. They also describe what pesticides are available to homeowners for domestic use.

For consumer-friendly health tips and information : Healthy Ontario.com

INFOline :
Tel :1-877-234-4343 toll free in Ontario
TTY : 1-800-387-5559

Telehealth Ontario :
Tel : 1-866-797-0000;
TTY : 1-866-797-0007

Or call your local public health unit.

May 2005

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