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Infectious Diseases

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999 Balmoral Street
Thunder Bay, ON
P7B 6E7
Phone: (807) 625-5900
Toll-Free: (888) 294-6630
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Mosquitoes and West Nile Virus

PLEASE NOTE:  The Health Unit has stopped the dead wild bird collection through the Crow Line as the province of Ontario is no longer testing these birds for West Nile virus. 

Click here for information on what to do with dead wild birds.


Click on the links below to learn more about mosquitoes and West Nile virus:


What is West Nile virus and how do people get infected?

West Nile virus (WNV) is spread to people through the bite of an infected mosquito.

Mosquitoes transmit the virus after being infected by feeding on the blood of birds that carry the virus.

WNV was first identified in the West Nile District of Uganda in 1937. Since then it has been found in Israel, Egypt, Romania, United States, Canada and Russia. It was first detected in North America in 1999 (New York) and since spread to Canada.



What is the risk of West Nile virus in the Thunder Bay District?

The risk of West Nile Virus to humans in the City and District of Thunder Bay is currently low.  There were no human cases of WNV in the Thunder Bay District in 2008, although two cases were reported during 2007.

Only 0.6% (less than 1%) of the mosquitoes tested in 2008 were the species (Culex restuans) that are able to transmit the WNV to birds and to humans.

Mosquitoes have tested positive for WNV in the health unit to the east (Algoma Health District) and one human case of WNV was reported in 2006 in the health unit to the west (Norhtwestern Health Unit).



How does the Health Unit monitor this area for West Nile virus (WNV)?

Mosquitoes are the bridge from infected birds to humans. To monitor this area for WNV, the Health Unit traps mosquitoes at various locations throughout the Thunder Bay District.  The mosquitoes are then sent for identification to determine the type of mosquitoes present in our area.  There are several species that have the potential to carry the WNV.  Only 0.6% (less than 1%) of the mosquitoes tested in 2008 were the species (Culex restuans) that are able to transmit the WNV to birds and to humans.



Is the Health Unit still collecting dead birds through the Crowline?

No, the Health Unit is no longer collecting.  Effective in 2009, the Ontario Ministry of Health and Long-Term Care will no longer be conducting a West Nile virus (WNV) dead bird surveillance program.  Dead corvids (crow family) are no longer required as an early indicator of WNV.  Information collected over the past few years has confirmed when and where the virus will most likely appear.  Ontario will continue to use other indicators, such as mosquito surveillance, to determine the human health risk of WNV in the province.



What do I do if I find a dead wild bird?

Please call the Canadian Cooperative Wildlife Health Centre to see if they want to make arrangements to collect and test the bird. The centre can be reached toll free at 1-866-673-4781.

To get rid of a dead wild bird

1. On your property:

  • Wear gloves (make sure there are no rips or tears).
  • Use a shovel if available.
  • Place the bird in a double bag and tie the bag tightly.
  • Get rid of the bird in the municipal garbage.


2.  City of Thunder Bay property:

  • Call animal services at 684-2156.



Where can I learn more about the status of West Nile virus in the Thunder Bay District?

Each year, a report on the status of WNV is prepared by Dr. Ken Deacon, the Health Unit’s bioconsultant.  Click on the links below to access the reports.   



What can I do to reduce mosquito breeding sites?

The best way to start is by getting rid of places where mosquitoes can breed:

1.  In standing water

  • Don't allow any outside water to stand for more than four days.
  • Cover rainwater barrels with mesh or screen.
  • Drill holes in the bottom of any unused containers so water can't collect.
  • Remove or drain any standing water from bird baths, discarded tires, flower pots, wheelbarrows, barrels or tin cans that are left outdoors.

2.  In swimming or wading pools

  • Remove any water that collects on pool covers.
  • Make sure the pool's pump is circulating water properly.
  • Turn over the water (e.g. move it around) in wading pools when not in use.

3. In your eaves and drains

  • Clear leaves and twigs from gutter, storm and roof gutters throughout the summer.
  • Make sure that drainage ditches are not clogged.
  • Check flat roofs often for any standing water.


4. Around your yard and lawn

  • Throw away lawn cuttings and raked leaves (e.g. sealed lawn bags).
  • Turn over compost piles (e.g. move it around) regularly.
  • Fill in any low areas on your lawns so water doesn’t pool.


5. Try to keep mosquitoes out of the house

  • Make certain that door and window screens fit tightly and do not have holes. If there are no screens, keep doors and windows closed from early evening to dawn.

*Material used with permission of the Halton Region Health Department.



How can I protect myself and my family from mosquito bites?

Mosquitoes are most active between dusk and dawn. If you are going to be outdoors during this time, cover up and use insect repellent for extra protection.

1.  Wear light-colored clothing:

  • long sleeved shirt or jacket
  • long pants tucked into socks

2. Use insect repellent:

  • Use an insect repellant with DEET. Click here for a fact sheet from Health Canada, including guidelines for use (infants, children, adults and pregnant women)



What are the symptoms of West Nile virus (WNV)?

Most people infected with the virus have no symptoms or they have flu-like symptoms. But, the virus can cause severe illness.  Click here for more information.



Is there a fact sheet I can read for more information?

You can find fact sheets with more information by clicking on the links below:

Ontario Ministry of Health and Long-Term Care 

  • English, French and 23 other languages

Public Health Agency of Canada

Health Canada



Where can I get more information on West Nile virus (WNV)?

For more information about mosquitoes and West Nile virus, please call a Public Health Inspector in the Infectious Disease program at 625-8318 or 1-888-294-6630, ext. 8318.


Last Updated: 4/20/2016