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Governance &
Structure Division

West Nile Virus and B.C. Local Governments


Programs to assist local governments and First Nations with West Nile Virus are available through the Union of BC Municipalities.

What is the West Nile virus?

West Nile virus (WNV) was first detected in North America in New York City in 1999 and has spread across the continent. WNV is a mosquito borne virus or "arbovirus" capable of causing human illness and death. The mosquitoes become infected when they feed on infected birds. Certain species of "bridging" mosquitoes transmit WNV when they then feed on humans or other mammals. WNV is not transmitted from person to person except by organ transplant, blood transfusion, or mother's milk.

Most people who become infected with West Nile have no symptoms at all (4 of 5 cases). The less severe symptoms of this illness are fever, headache, and body aches. However, there is particular concern about a more serious expression of West Nile that can result in severe neurological effects in the long term. Overall, one in 150 infections results in severe neurological illness such as encephalitis or meningitis. For more information about health risks in BC, please check with the Office of the Provincial Health Officer or HealthLink BC.


Where is it now?

B.C. has some regions where warm temperatures, mosquito populations capable of transmitting West Nile, and urban population concentrations produce conditions conducive to virus transmittal to humans. Tracking the spread of West Nile involves local health authorities collecting dead corvids (crows, jays, magpies) and mosquitoes. These are submitted to the BC Centre for Disease Control to be tested. Please contact the BCCDC for up-to-date information about West Nile or use their Interactive GIS Mapping for West Nile Virus.

Bird testing in provinces and states near BC has positively identified the West Nile virus. Use the links below to check provincial, Canadian, and North American maps to track the spread of the virus. Bird dispersion through east-west mountain passes (from Alberta), and up north-south river valleys (from Washington, Idaho, or Montana) will be the most likely way that West Nile virus will enter B.C.


Who is doing what?

Mosquitoes are ordinarily handled as nuisances and many local governments have established mosquito control services. With the arrival of West Nile virus in western Canada, mosquito control also became a health issue and provincial and federal governments have become involved.

Public Health Agency of Canada coordinates a national approach to West Nile including surveillance, blood screening, pesticide regulation, information, and First Nations involvement. The Health Canada web site is a good place to start for information on West Nile.

The Provincial Health Officer (PHO) is the senior medical health officer for BC. The PHO would work with Medical Health Officers and the B.C. Centre for Disease Control in affected regions. Further details can be found on the PHO web site.

Ministry of Environment normally issues permits for pesticide use where mosquito control is required.

Regional Health Authorities (RHAs) undertake the public health function in their regions. Medical Health Officers inform and advise local governments about the health issues associated with West Nile virus. Please visit your health authority site for regional information.


The BC Centre for Disease Control (BCCDC) coordinates the provincial response to public health risks. The BCCDC has established guidelines for surveillance and response that categorize levels of WNV alert:

Response levels
  • 0 - no confirmed arbovirus infection in bird, animal, or mosquito pool
  • 1 - no confirmed arbovirus infection, arbovirus activity is possible or risk unknown
  • 2A arbovirus activity previous year or in neighboring jurisdiction
  • 2B detection of arbovirus activity within a jurisdiction in the current year
  • 3 detection of single or multiple human cases of arbovirus infection

Please refer to the BCCDC site for more information on the status of West Nile.

Ministry of Community, Sport and Cultural Development is providing input into provincial response planning to ensure that local governments are kept informed of the progress of West Nile and appropriate responses to it.

Other Provinces and States have substantial programs to combat West Nile virus. Some programs have been in operation for since 2004.

Idaho State
Washington State
US Centre for Disease Control


What can local governments do?

Because of the potential threat from West Nile virus, local governments should start planning for its arrival with the following activities:
  1. Planning for West Nile mosquito control
    Some local governments where West Nile virus may arise have already developed a response plan, mapped mosquito breeding areas and larval occurrence, and began larvaciding.
  2. Preventative measures
    Web and print information can be provided to the public about the possible presence of West Nile and measures people can take to prevent it. Your Health Authority often coordinates these tasks.
  4. Control of standing water on private land
    Health authorities and municipalities are encouraging landowners to monitor and control standing water on their land. Standing water control minimizes the breeding areas for "bridging" species of mosquitoes that bite both birds and people.
  5. Treatment of municipal lands and structures
    Larvaciding, where appropriate, has proven to be a relatively inexpensive and effective means of reducing mosquitoes on local government land and in storm drains. Please see the Halton, Ontario site for more information on all aspects of mosquito control and West Nile virus.

Adulticiding, where adult mosquitoes are sprayed with pesticides, will only be considered where there is significant human health risk. This decision will be made by the local MHO in consultation with a local advisory group, the BCCDC and the PHO.



B.C.’s West Nile virus strategy was developed by a provincial working group including public health inspectors, physicians, veterinarians, wildlife experts, entomologists and pesticide officers. Representation also includes those from the BCCentre for Disease Control, regional health authorities and the provincial ministries of Health, Environment and Agriculture.

Please contact the West Nile virus Co-ordinator for more information about the Ministry of Community, Sport and Cultural Development's role in West Nile virus issues.

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