Busy season for mosquitoes, West Nile virus

WATERLOO REGION — Three cases of West Nile virus have been reported in Waterloo Region this year, including one case that was locally acquired.

This summer was an especially good one for mosquitoes, with the prolonged heat producing a “more robust population.”

“This year with the warm weather it definitely made a difference,” said Brenda Miller, manager of health protection and investigation with the region.

Nine mosquito traps scattered throughout the region tested positive for West Nile virus — considerably more than usual.

In an average year, only two or three pools test positive in the region. In Ontario, 283 pools tested positive, which meant the virus was prevalent across the province this summer.

It’s not unusual to see a small number of human cases each season, most related to travel to areas known to be a higher risk for the virus. West Nile is reportable to public health, which then investigates cases to determine when the symptoms appeared and when and where it was likely the person was infected.

Miller said public health cannot talk specifically about the cases or if any of the people became seriously ill.

Most people do not experience any symptoms when infected with the virus.

For those who do become sick, mild flu-like symptoms can occur three to 15 days after being bitten by an infected mosquito. Those include mild fever, headache, muscle aches, stiff neck, swollen glands and rash.

Less than one per cent of people who are infected experience severe illness involving the central nervous system.

While summer may be waning, Miller urges people to continue take precautions to avoid being bitten by a mosquito as the risk of West Nile is still there.

“They’re still looking for a blood meal to see them through the season,” Miller said.

West Nile virus is spread when a mosquito feeds on an infected bird and then bites a person.

When outdoors, particularly between dusk and dawn, wear protective clothing (light-coloured, tightly woven longsleeved shirts, pants, socks, shoes and a hat) and apply a repellent containing DEET or Icaridin. Around the house, eliminate standing water where mosquitoes can breed and ensure there’s no way for them to get inside.