Communicable Diseases - West Nile Virus

Communicable Disease Prevention and Control

West Nile Virus - Insect and Animal-Related Diseases

West Nile virus is a viral infection transmitted by mosquitoes.  Mosquitoes pick up the virus from feeding on birds and then can transmit the illness to humans.  The risk of west Nile virus in Nova Scotia is very low.

There have been no human cases of West Nile virus acquired in Nova Scotia.

Starting in 2010 dead birds in Nova Scotia will no longer be routinely tested for West Nile virus. No birds have tested positive since 2003.  If clusters of dead birds are noticed, this may be due to a number of causes so it is important to contact the local Department of Natural Resources.

What are the symptoms?

Most people who are infected with WNV have no symptoms. Some people will have a fever, headache, muscle weakness and body aches. A few people will experience more severe forms of WNV such as encephalitis or meningitis (swelling of the brain or the lining of the brain). The symptoms of encephalitis/meningitis may include a rapid onset of severe headache, high fever, stiff neck and disorientation.

What is the treatment?

There is no specific treatment for WNV infection. Therefore, prevention is very important.

How Can You Prevent West Nile Virus?

Avoiding mosquito bites is the most important way of preventing WNV infection.

  • Stay indoors at dawn, dusk, and in the early evening.
  • Wear long-sleeved shirts and long pants whenever you are outdoors.
  • Spray clothing with repellents containing permethrin or DEET since mosquitoes may bite through thin clothing.
  • Apply insect repellent sparingly to exposed skin. An effective repellent will contain 35% DEET). DEET in high concentrations (greater than 35%) provides no additional protection.
  • Repellents may irritate the eyes and mouth, so avoid applying repellent to the hands of children. Do not apply DEET repellants more than 3 times per day for children aged 2 to 12 years old. Use DEET on children aged 6 months to 2 years only when there is a high risk of infections from mosquito bites, and only apply once daily. Do not use DEET on children less than 6 months of age.
  • Whenever you use an insecticide or insect repellent, be sure to read and follow the manufacturer’s DIRECTIONS FOR USE, as printed on the product.
  • Eliminate potential mosquito breeding sites around your home.
    • Eliminate standing water in such things as pool covers, flower pots, children’s toys, old tires etc.
    • Clean clogged roof gutters on an annual basis, particularly if the leaves from surrounding trees have a tendency to plug up the drains. Roof gutters are easily overlooked but can produce millions of mosquitoes each season.
    • Turn over plastic wading pools when not in use. A wading pool becomes a mosquito producer if it is not used on a regular basis.
    • Turn over wheelbarrows and change water in bird baths at least twice weekly. Both provide breeding habitat for domestic mosquitoes.
    • Aerate ornamental pools or stock them with fish. Water gardens may become major mosquito producers if they are allowed to stagnate.
    • Clean and chlorinate swimming pools that are not being used.
    • Use landscaping to eliminate standing water that collects on your property. Mosquitoes can develop in any puddle that lasts more than 4 - 8 days.
    • Mosquito breeding around the home can be reduced significantly by reducing the amount of standing water available for mosquito breeding.

Mosquitoes and You

There are steps you can take to decrease your chances of being bit by mosquitoes.

Steps to reduce mosquito bites include:

  • Make sure that door and window screens do not have holes and fit tightly.
  • Avoid exposing skin at dawn, dusk and in the evenings when mosquitoes are most active.
  • If you must be outdoors during peak mosquito times, wear long-sleeved shirts and pants.
  • Wearing light coloured clothing is recommended as mosquitoes are attracted to darker colours.
  • Special screen mesh clothing is available in the form of screen jackets, suits and head nets. These are available at most hardware and department stores, as well as camping and outdoor supply shops.
  • There are many insect repellents available. Be sure to read and follow the manufacturer’s DIRECTIONS FOR USE whenever you use these products.
  • Do not apply insect repellents to children under 2 years of age. Avoid applying repellent to the hands of older children.
  • Spray clothing with repellents containing DEET or permethrin, as mosquitoes may bite through thin clothing.

More information can be obtained at the Health Canada web site:

Other Resources:

West Nile Virus - Protect Yourself!
Public Health Agency of Canada
West Nile Virus
Centers for Disease Control and Prevention ( USA )
West Nile Virus (WNV)
Canadian Blood Services and West Nile Virus