Media Release

September 12, 2011

York Region reports first case of West Nile virus

Lab results confirm one human case has tested positive for WNV
NEWMARKET – The Regional Municipality of York is reporting an individual from the City of Vaughan has tested positive for West Nile virus (WNV), making it the first positive human case of the year in York Region.
“Although late in the season, the risk of exposure to infected mosquitoes still remains high,” said Dr. Karim Kurji, York Region’s Medical Officer of Health. “We continue to advise York Region residents to take necessary precautions to protect themselves, especially during times when mosquitoes are most active.”
Trapping mosquitoes, larviciding and human surveillance are part of the 2011 York Region WNV control plan. 
WNV illness can range from mild symptoms, including rash, joint pain and fever to more severe symptoms, including confusion, severe headache and a sudden sensitivity to light. In rare cases, neurological illness, including encephalitis (inflammation of the brain), can also occur. Symptoms of WNV typically appear three to 15 days after being bitten by an infected mosquito. Those experiencing symptoms should seek
medical advice.
Prevention and protection are the best ways to protect yourself and your family from WNV. There are simple and common sense precautions that should be taken:
• Minimize outdoor activities where and when mosquitoes are most active such as dusk, night and dawn
• Wear protective clothing such as long sleeved shirts, full-length trousers, socks, light coloured clothing and tuck pant legs into socks when possible
• Apply an insect repellent, as directed
• Make sure screens on your home are tight-fitting and in good repair
• Mosquitoes breed in still water; eliminate stagnant water around your property which may gather in pool covers, flower pots, children’s pools, old tires and birdbaths
The 2011 York Region West Nile virus (WNV) Control Plan includes:
• Public education regarding effective measures to prevent exposure to WNV
• Mosquito and human surveillance
• WNV control activities, including a larviciding strategy:
• Four larvicide applications take place over the summer months. These applications target all catch basins along Regional and municipal roads and in catch basins on private property, as required.
• Methoprene is the larvicide used. It comes in a slow-release pellet-like formulation and is administered in catch basins when the mosquito is in the larval stage of development. It interferes with the mosquito life cycle, preventing the mosquito larva from reaching maturity. It is not sprayed. It has been approved by both the provincial and federal governments and is considered low risk for humans, pets and the environment when it is applied according to label directions.
• Larvicide is applied by licensed Ministry of the Environment applicators. Treated catch basins are marked with a coloured dot.
• Residents who are concerned about catch basins on private property are requested to place a mesh screen over the catch basin to prevent mosquitoes from entering and exiting. Rear-yard catch basins located on private property will be treated by request.
• In addition, the larvicide Bti. and Bacillus sphaericus may be placed in ditches and temporary or permanent standing water pools, including storm water management ponds, if evidence of mosquito breeding is found. These are naturally occurring bacterium found in the soil.
For more information on WNV or any or public health-related concern, contact York Region Health Connection at 1-800-361-5653 or TTY 1-866-252-9933
To review the current status of WNV in Ontario, visit
For more information on West Nile virus, visit

- 30 -
Media Contact: Jennifer Mitchell-Emmerson, Community and Health Services, York Region
 1-877-464-9675, ext. 4016 • Cell: 905-955-2533 •

- 30 -
Media Contact: Michelle McEwan, Corporate Communications, York Region
  1-877-464-9675, ext. 1209 . Cell: 905-251-6412 .
Founded in 1971, The Regional Municipality of York is made up of nine municipalities
and provides services to more than one million residents, 29,000 businesses and 495,000 employees.

 For more information visit us at Follow us on : York Region   @YorkRegionGovt  
Back to top