DURHAM: Durham Region Health Department has started West Nile virus (WNV) surveillance and control activities for the 2019 season.
WNV is a mosquito-borne disease, spread to humans through the bite of an infected mosquito. Mosquitoes become infected by feeding on the blood of birds who carry the virus. The disease is not passed from person to person or from bird to person.
As part of its ongoing WNV surveillance activities, the Health Department routinely traps batches of adult mosquitoes, known as mosquito pools, which are then tested for the virus. In 2018, seven of the mosquito pools trapped by the Health Department tested positive for WNV. This represents a decrease from 10 positive mosquito pools in 2017. In addition to testing adult mosquitoes for the virus, the Health Department also uses indicators such as larval mosquito surveillance to determine the risk of WNV for area residents.
“Mosquitoes lay their eggs in standing water, these eggs then become mosquito larvae,” explained Ross MacEachern, Manager, Health Protection with the Health Department. “Therefore, area residents are reminded to remove or cover any standing water around their homes, to help reduce the development of mosquito larvae.”
Since 2001, WNV has been found in birds, mosquitoes, horses and humans in Ontario. For 2018, the Public Health Agency of Canada reported 126 human cases of the virus in Ontario, compared to 155 human cases in 2017. Durham Region had five confirmed human cases of WNV in 2018, compared to three human cases in 2017.
The Health Department recommends the following specific steps to help minimize potential breeding sites for mosquitoes: Chlorinate rain barrels or cover them with mosquito screening; Drain water from areas such as pools and chair covers, and from containers such as ceramic pots, wading pools, bird baths, planters, etc; Check that roof gutters are cleared and draining properly; Clean and properly maintain swimming pools and outdoor hot tubs; Remove all unused tires from your property; Ensure drainage ditches are not backed up.
To help reduce the possibility of being exposed to WNV, residents are encouraged to take the following precautions: Wear shoes, socks and light-coloured clothing with long sleeves and full-length pants when outside, especially overnight, between dusk and dawn, when mosquitoes are most active; Use insect repellent containing DEET on exposed skin, following Health Canada’s safety tips on using personal insect repellents. More information on using insect repellents containing DEET can be found at https://www.canada.ca/en/health-canada/services/about-pesticides/insect-repellents.html?_ga=1.190416748.61038264.1464190033; Ensure doors and windows have screens that are tight-fitting and good repair; Keep grass, shrubs and hedges trimmed; and Turn over compost piles regularly.
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 identifying stagnant water sites where mosquitoes could breed.
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 durham.ca/WestNile.
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