The Regional Municipality of Durham

News Release

Health Department begins 2017 West Nile virus surveillance activities

WHITBY, ON May 26, 2017 - Durham Region Health Department has started West Nile virus (WNV) surveillance and control activities for the 2017 season. WNV is a mosquito-borne disease that is spread to humans through the bite of an infected mosquito. Mosquitoes become infected by feeding on the blood of birds that carry the virus. The disease is not passed from person to person or from bird to person.

WNV has been found in birds, mosquitoes, horses and humans in Ontario since 2001. In 2016, the Public Health Agency of Canada reported 46 cases of the virus in Ontario, compared to 33 in 2015. Durham Region reported one confirmed and one probable human case of WNV in 2015 and 2016, respectively.

The Health Department has routinely trapped adult mosquitoes as part of its ongoing WNV surveillance activities. In 2016, 10 of the mosquito pools that were trapped tested positive for WNV, compared to no positive mosquitoes trapped in 2015. In addition, as part of seasonal WNV monitoring activities, the Health Department also uses indicators such as adult and larval mosquito surveillance to determine the risk of WNV for area residents. “Mosquitoes lay their eggs in standing water,” explained Ross MacEachern, Manager, Environmental Health with the Health Department. “As a result, area residents are reminded to remove or cover any standing water around their homes to help reduce the development of mosquito larvae.”

The Health Department recommends the following specific steps to help minimize potential breeding sites for mosquitoes:

To help reduce the possibility of being exposed to WNV, residents are also encouraged to take the following precautions:

Throughout the summer, the Health Department will conduct a number of activities to monitor WNV concerns across the Region, including implementing a weekly adult mosquito-trapping program, a larval mosquito surveillance program and a larviciding program involving regional catch basins, as well as identified mosquito breeding stagnant water sites. For more information on WNV and the Health Department’s surveillance activities, please call the Health Department’s Environmental Help Line at 905-723-3818 or 1-888-777-9613, or visit

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Media inquiries:
The Regional Municipality of Durham
Glendene Collins - Health Department, 905-668-7711 ext. 2999 or

If this information is required in an accessible format, please call 1-800-841-2729 ext. 3094.

For more information, please contact Health Department.