August 8, 2005

First birds test positive for West Nile Virus

NEWMARKET: York Region Health Services reports that two dead crows have tested positive for West Nile Virus (WNV). One crow was found in the Town of Markham, close to the intersection of Steeles Avenue East and Leslie Street. The second was found in the City of Vaughan, close to the intersection of Jane Street and Teston Road. The birds were picked up through the WNV surveillance program. They are the first positive birds reported in York Region this season.
Last year, the first positive bird in York Region was reported May 26th and was found in the Town of Aurora. There were a relatively low number of WNV cases reported in 2004, with no human cases*, 11 birds and 1 mosquito pool testing positive for the virus in York Region. The Ministry of Health and Long-Term Care did not attribute any deaths in the province last year to WNV illness.
There have been five reported cases of WNV in humans in Ontario in 2005, to date. None have been reported in York Region.
Like humans, WNV is transmitted to the bird population by infected mosquitoes. Crows, blue jays and other raptor species are known to be most susceptible to the disease and act as early warning signs for the presence of the virus in a particular area.
Report dead crows and blue jays. York Region Health Services requests that residents report sightings of dead crows and blue jays through the Health Connection information line. Suitable specimens may be collected and submitted to the Canadian Co-operative Wildlife Health Centre in Guelph for testing. All crows and blue jays that are reported will help to map out possible WNV activity in York Region.
Dead bird pick-up service is available. Most dead birds will not be suitable for testing, but knowing what species they are and where they died is important information. Do not handle birds with bare hands or dispose of dead birds through the municipal garbage systems. Please contact Health Connection for pickup of dead birds of any species.
The symptoms for WNV illness consist of fever, muscle weakness, stiff neck, confusion, severe headache, and a sudden sensitivity to light. For a very rare few, the virus causes serious neurological illness including encephalitis (inflammation of the brain). 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.
• Consider using 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 York Region WNV control plan for 2005 includes:
• Mosquito, bird and human surveillance
• WNV control activities, including a larviciding strategy:
- The strategy includes four larvicide applications (in June, July, August and September). Two larvicide applications have now been completed. These applications target all catch basins along Regional and Municipal Roads and in catch basins, as required, on private property
- Methoprene is the larvicide that is 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
• The WNV control plan also includes public education regarding common sense and effective measures to prevent exposure to WNV

To report a dead crow or blue jay and for more information on WNV or any health-related concern, contact York Region Health Services Health Connection at 1-800-361-5653 or visit
To review the current status of WNV in Ontario, visit


* One 2004 York Region probable human case listed on the Ministry of Health and Long-Term Care website may have been exposed to the virus while travelling out of province and is not included in York Region statistics.

Contact:  Kim Clark, York Region Health Services
   905-830-4444 Ext. 4101

Back to top