West Nile Virus: Age and Group Specific Information

West Nile Virus (WNV) impacts certain groups in the community in different ways. To help with this, specific information is available for the following groups:

  • Older adults
  • Children
  • Mothers
  • Home and Property Owners
  • Neighbours
  • Outdoor Workers and their Employers
  • Horses and Other Pets
  • Campers and Outdoor Enthusiasts


Older adults

Although WNV has been identified in a wide range of ages, adults over 50 years of age are more likely to develop encephalitis or swelling of the brain.

They may also experience prolonged muscle weakness and neurological problems. This is a serious illness, with recovery taking up to a year. By following simple steps to 'fight the bite', the risk of illness decreases.

For more information, please refer to our Personal Protective Measures Fact Sheet.


Although children are not at any greater risk of becoming infected with WNV, caution should be used when applying DEET to children.

Remember to use the lowest concentration needed for the time outside and never use DEET on children under six months of age.

For more information, please refer to our Personal Protective Measures Fact Sheet.


There is evidence that pregnant women can pass WNV to their unborn babies and that lactating women can pass the virus to their babies through breast milk.

As a result, these women are encouraged to take precautions to 'fight the bite' and minimize exposure to mosquito bites.

Note there is no evidence that the use of DEET by pregnant or lactating women poses a hazard to unborn or nursing children. However, as a safety precaution consider using non-chemical methods to prevent mosquito bites.

For more information, please refer to our Personal Protective Measures Fact Sheet and Pregnancy and Personal Protective Measures Fact Sheet.

Home and property owners

Research shows that adult mosquitoes are usually found close to their original larval breeding sites.

To minimize exposure, home and property owners should remember the following tips:

  • Remove standing water around the home. Standing water acts as a breeding ground for mosquitoes.
  • 'Screen mosquitoes out' of the home by fixing holes in window screens and other places they can enter.

For more information, please refer to our Personal Protective Measures Fact Sheet.


If a neighbour has standing water on their property, you can call Region of Waterloo Public Health at 519-575-4400 to report the address of the property of concern.

A letter outlining recommendations to remove standing water and health concerns related to standing water will be sent to the property owner.

You may also wish to check with your local municipality to see if they have any by-laws relating to standing water.

West Nile Virus and sunscreen

Anyone using sunscreen should first apply sunscreen and allow it to absorb for 30 minutes. Insect repellent can then be applied onto the skin, but it shouldn't be applied under clothing.

Although there are some insect repellent products which contain sunscreen compounds, these should be used with caution. This is because insect repellents should be applied sparingly, sunscreens should be applied liberally and frequently.

These products have been reviewed by Health Canada's Pest Management Regulatory Agency (PMRA) and effective December 2003, will no longer be registered for use. For more information, please refer to our Personal Protective Measures Fact Sheet.

Outdoor workers and their employers

Outdoor workers face a greater risk of exposure because they are more likely to come in contact with mosquitoes.

As a result, outdoor workers should be particularly careful to learn about the risks of WNV and take preventative measures to minimize exposure.

Employers can obtain educational materials on WNV by contacting Region of Waterloo Public Health at 519-883-2008 ext. 5147 or downloading them from our website.

Campers and outdoor enthusiasts

Campers, hikers and other outdoor enthusiasts, who spend a significant amount of time outside, are at increased risk of exposure.

To minimize exposure to bites, it is important to make personal protection a priority when going outside.

For more information, please refer to our Personal Protective Measures Fact Sheet.

Horses and other pets

WNV infections have been reported in a wide range of animal and bird species, including horses, dogs, cats, deer, crows, chickens, geese, jays, raptors and owls.

An equine vaccination product for horses is available from veterinarians in North America. The Ontario Ministry of Agriculture and Food encourages the vaccination of horses for WNV.