West Nile Virus and Seniors

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What is West Nile Virus?

West Nile Virus (WNV) is a virus that is found in wild birds and carried by mosquitoes. It was first identified in the province of West Nile, Uganda in 1937. Since then it has been identified all over most of the world. In 1999, it was first identified in New York State in the United States and in the summer of 2001, it was discovered in birds in southern Ontario. The virus has continued to spread to other areas of Canada.

How is West Nile Virus spread?

Mosquitoes become infected with West Nile Virus when they feed on the blood of infected birds. The virus is carried in the mosquito's salivary glands. An infected mosquito can then transmit WNV to humans and animals when it takes a blood meal. The virus is not known to spread from person-to-person contact, such as touching, kissing or caring for someone who is infected. Other modes of transmission are being investigated.

Are older adults more at risk from illness associated with West Nile Virus?

Older people are at no greater risk of being bitten by a mosquito infected with the West Nile Virus than any other person. However, persons over 50 or those with weakened immune systems are at greater risk of becoming ill if bitten by an infected mosquito. The most significant risk factor for developing severe symptoms requiring hospitalization is advanced age.

What are the symptoms of West Nile Virus?

Most people who are infected with the West Nile Virus will not have any type of illness. For those who do become ill, symptoms can begin 3 to 12 days following the bite of an infected mosquito. Symptoms include mild fever, headache, stiff neck, muscle weakness, skin rash, and swollen lymph glands. In rare cases, these symptoms may progress into a serious illness involving inflammation of the brain (encephalitis) and spinal cord (meningitis) and possibly death. If you are experiencing any of these symptoms contact your doctor immediately.

How is West Nile Virus treated? Is there a vaccine?

There is no specific treatment or vaccine for West Nile Virus; however, the symptoms and complications can be treated. Most people recover from the infection.

If I live in an area where West Nile Virus is reported and a mosquito bites me, am I likely to get sick?

The chances of being bitten by an infected mosquito are small. To reduce your chances even further it is important to take personal protective measures and reduce mosquito breeding grounds around your home. For more information please refer to the fact sheet entitled Protect Yourself from Mosquito Bites

What can I do to reduce my risk of becoming infected with West Nile Virus?

The types of mosquitoes that usually transmit WNV are active and feed in the evening and morning. Mosquitoes can also be active during the day in shaded or wooded areas. If you are outdoors during these times or in these locations it is recommended that you wear lightly coloured long-sleeved shirts, long pants, socks, and shoes when outdoors. If you choose, you can use an insect repellent, preferably containing DEET. Insect repellents can dry skin, which is a significant problem for those with thin skin. Health Canada does not approve skin moisturizer and insect repellant combination products. Use separate products simultaneously when required. Reapplication of the repellent may be required if outdoors for extended periods (greater than 2 hours).

What can I do around my home to protect myself from exposure to mosquitoes?

A typical yard can generate thousand of mosquitoes every week. Mosquitoes usually fly and feed within 1-3 km from the breeding site. The key to prevention is taking the appropriate precautions to reduce the mosquito population around your property. Mosquitoes lay their eggs in standing water. Limit the number of places around your home for mosquitoes to breed by getting rid of items that hold water. Remove or change all standing water around your home (turn over or throw out containers that hold water and change water in bird baths every two to three days) to reduce potential mosquito breeding areas.

Reduce mosquito breeding grounds by:

• Once or twice a week, empty water from flowerpots, birdbaths, buckets, and rain barrels.
• Ornamental ponds or fountains should be drained or cleaned weekly.
• Ensure window and door screens are intact. Keep mosquitoes outside by having well-fitting, tear-free screens on both windows and doors.
• Check for clogged rain gutters and clean if necessary.
• Check for containers or trash that may hold water in places that may be hidden, such as under bushes.
• Ensure timed watering systems are functioning correctly; do not over water.
• Keep property ditches dry.

Source: Health Canada, Ontario Ministry of Health and Long Term Care, Centers for Disease Control