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What is West Nile virus?

West Nile virus (WNV) is a mosquito transmitted virus that can be transferred to humans from the bite of an infected mosquito. The first confirmed case in Canada was in 2002.  

How is West Nile virus spread?

Mosquitoes become infected with WNV when they feed on infected birds. The bite by an infected mosquito can then transmit WNV to humans and other animals. The virus is not known to spread through touching, kissing, or caring for someone who is infected.  In very rare cases, WNV can be spread through blood transfusion, organ or tissue transplants, during pregnancy from mother to baby, breast milk, or exposure of laboratory workers to infected medical specimens.

Who is at risk for West Nile virus?

People of all ages can be infected with West Nile virus. The risk of severe illness increases with age and is greater for people with chronic diseases or weakened immune systems.

What are the symptoms of West Nile virus?

No Symptoms

Most people (70-80%) who get WNV will not get sick or experience any symptoms.

Mild Symptoms

Almost 20% of those infected will have West Nile fever, which consists of fever, headache, body aches, swollen lymph nodes, and mild rash. These symptoms can last for as short as a few days to as long as several weeks.

Severe Symptoms

Very few people will develop severe symptoms that affect the central nervous system. These include:  quick onset of severe headache, high fever, muscle weakness, stiff neck, vomiting, confusion, paralysis. These symptoms may last several weeks, and neurological effects may be permanent.

If you experience sudden onset of any of the symptoms listed above, seek medical attention immediately. While there is no treatment or vaccine for WNV, symptoms can be treated.

How can I protect myself and my family from West Nile Virus?

The best way to avoid WNV is by not being bitten by mosquitoes. For more detailed information on protection please refer to our web pages on Mosquito Safety.

What should I do about “standing water” (water that does not move)?

It is important to remove any standing water on your property.  Mosquitoes use standing water to lay eggs.

  • Remove standing water around your home (e.g., bird baths, flower pots , eavestroughs/gutters).
  • Keep pools clean and chlorinated, and aerate ornamental ponds.
  • Cover rain barrels with screens
  • Keep wheelbarrows and plastic wading pools turned over when they aren’t being used.
  • For water that cannot be emptied or changed (e.g., ponds), use an approved mosquito larvicide (look for a Pest Control Product (PCP) number) that either kills larvae or stops development.
  • Keep grass cut.

Who should I call about “standing water” on someone else’s property?

If you have a standing water complaint, please contact your municipality.

What should I do if I find a dead bird on my property in Windsor-Essex County? 

If you find a dead bird report it to Canadian Cooperative Wildlife Health Centre by calling 1-866-673-4781.

If you need to dispose of a dead bird, use rubber gloves and a shovel to handle it.  You can:

  • bury the dead bird at least 3 feet deep (not in a vegetable garden), or
  • double bag the dead bird in a sealed plastic bag and place it in the garbage bag for pickup.
  • Throw away the rubber gloves and wash your hands with soap and water thoroughly after handling dead birds.

Note: The Health Unit no longer collects and tests dead birds for West Nile virus. 

What is being done about West Nile virus in Windsor-Essex County?

The Windsor-Essex County Health Unit works with local municipalities to reduce the impact of WNV.  The Health Unit and municipalities have contracted a service provider to run the WNV surveillance and treatment program in our area. The program includes:

Adult Mosquito Surveillance and Analysis

The black-light CDC traps are set up at various locations throughout Windsor – Essex County to capture mosquitoes for testing to determine the presence of West Nile virus in our area. These traps have a light and dry ice that attracts the mosquitoes. The mosquitoes fly into the trap, get caught in the net, and are then collected for testing. The mosquitoes trapped are counted and tested to identify the species and determine if any of the mosquitoes are carrying the virus.

Mosquito Larviciding Program

Larviciding is the use of pesticides to control specific species of insects such as mosquitoes. Larvicides are a type of pesticide that kill mosquito larvae before they develop into adult mosquitoes. The larvicides are applied to catch basins, standing water sites, and lagoons that hold water and breed mosquitoes.

Larvacide is typically applied from June to the end of August; however the exact start date will depend on larvae mosquito surveillance results.

Will I be kept informed?

The Windsor-Essex County Health Unit will keep you informed about West Nile virus through media releases, pesticide use notices posted in local papers, the Health Unit’s website, social media, and the distribution of information at locations throughout the county.

What were the results of West Nile virus surveillance and treatment program in our area?

Results of the West Nile surveillance/treatment program for 2014, 2015, 2016, 2017 and 2018
Surveillance/Treatment 2014 2015 2016 2017 2018 2019
Mosquito Pools Positive for WNV 1 15 10 29 27 19
Mosquito Pools Tested for WNV 411 797 779 631 1054 979
Larvicide Applications to Roadside Catch Basins 105,264 115,010 118,641 128,283 133,283 137,311
Larvicide Applications to Standing Water Sites 72 11 40 81 71 201
Probable Human Cases Reported 0 3 2 1 0


Confirmed Human Cases Reported 1 1 2 20 13 1

For more information:

Speak with a Public Health Inspector by calling 519-258-2146 ext. 4475, or visit and search ‘West Nile virus’.

Information for Health Care Providers

Please report West Nile virus to the Health Unit immediately by phone 519-258-2146 or by fax 519-258-8672 (Monday to Friday from 8:30 a.m. to 4:30 p.m.). After hours, weekends, and holidays by phone at 519-973-4510.

Key References:

Government of Canada. (2016). West Nile Virus. Retrieved from

Centers for Disease Control and Prevention. (2016). West Nile Virus. Retrieved from

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