First mosquitoes test positive for West Nile Virus - July 20

HAMILTON , ON - July 20, 2017 -  Residents are reminded to take precautions against West Nile Virus (WNV) infection after Hamilton Public Health Services received results of West Nile virus positive mosquitoes in one mosquito trap within the city.

This is the first positive result for Hamilton this year. One mosquito pool (batch of mosquitoes) was positive among the mosquitoes collected on July 18 from one out of the 19 traps that are set weekly across the city. The City of Hamilton continually assesses the risk for human illness and has a comprehensive surveillance and prevention program.

The current risk for Hamilton has moved from low to moderate based on receiving these positive results. 

While most people infected with West Nile virus will have no symptoms (~80 per cent), others including older adults or those with weakened immune systems may experience West Nile fever (~20 per cent) or they may develop more severe illness including inflammation of the brain or the lining of the brain (~1 per cent). For any infection, if symptoms do occur, they appear two to 14 days after being bitten by an infected mosquito. 

Mosquito results and areas of the city

• One positive pool from one trap located in Lower Central Hamilton.

As part of its prevention efforts, the City recently completed the first round of larviciding treatments on city street catch basins and a second round is currently underway. Treatment of surface waters on public land is also ongoing. 

Additional resources

• Public Health Services reminds residents to avoid being bitten by mosquitoes
• The most effective defense is to use a mosquito repellent (bug spray) containing DEET. When using mosquito repellent, carefully follow manufacturer's instructions
• Other ways to prevent bites include avoiding areas where mosquitoes are known to be present or  covering up with light coloured long sleeves and long pants when in mosquito areas such as wooded areas, on the golf course, or in the garden, especially at dawn and dusk when mosquitoes are most active
• Remember to continue to remove standing water at least weekly from your property
• For additional information on West Nile virus please call 905-546-2489 during business hours, or visit www.hamilton.ca/westnile
• For more information visit Public Health Ontario - West Nile Virus Surveillance