First case in Hamilton of West Nile Virus in one human

HAMILTON, ON – The City of Hamilton has received confirmation of the first local human case of West Nile virus (WNV) this season prompting the Medical Officer of Health to move the WNV risk from moderate to high.

Residents are reminded to protect themselves against mosquito bites and to remove standing water from private property to prevent mosquito breeding.

While most people infected with West Nile virus will have no symptoms (approximately 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.

Take precautions to avoid being bitten by mosquitos

• Use a mosquito repellent (bug spray) containing DEET or Icaridin.
• Avoid areas where mosquitoes are known to be present or cover up by wearing 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.
• Reduce mosquito breeding sites by removing standing water at least weekly from your property. Mosquitoes lay their eggs in very shallow standing water. If you remove the standing water, they cannot lay eggs.

The City of Hamilton continually assesses the risk for human illness as part of a comprehensive West Nile Virus surveillance and prevention program. The City has completed three rounds of larviciding treatments on city street catch basins, in addition to ongoing treatment of surface waters on public land. The first batch of West Nile positive mosquitoes were found in late August, prompting the Medical Officer of Health to increase the risk level at the time from low to moderate.

“It is important to take precautions to avoid illnesses spread by insects including West Nile Virus, Lyme disease, and Eastern equine encephpalitis. Employing simple preventive measures such as using insect repellent containing DEET or Icaridin, covering up, and removing standing water on your property to prevent mosquito breeding will reduce your risk while you enjoy the outdoors. The risk of these infections will drop once there is a heavy frost that reduces the number of mosquitoes.” - Dr. Bart Harvey, Associate Medical Officer of Health, Hamilton Public Health

Additional resources

• For additional information on West Nile virus and the City’s mosquito control program, visit www.hamilton.ca/westnile or call 905-546-2489.
• Learn more about EEE virus
• Information on mosquito control on horse farms from Ontario’s Ministry of Agriculture, Food and Rural Affairs
• Hamilton’s Standing Water By-law(PDF, 61.33 KB)
• Public Health Ontario – West Nile Virus Surveillance