Public health officials in Ottawa are warning residents after the West Nile Virus was found in the city's mosquito population, but there are no human cases reported thus far.

Routine surveillance found the disease, which is spread by mosquitoes and can cause serious illness.

Most people do not feel symptoms if infected but about 20 per cent, especially the elderly and those with weakened immune systems, could experience flu-like symptoms such as headaches, muscle aches and pain.

Ottawa Public Health has a list of tips to avoid infection:

  • Wear long-sleeved light-coloured shirts and pants, socks.
  • Make sure door and window screens fit tightly and have no holes that may allow mosquitoes indoors
  • Reduce standing water sites around your home (bird baths, toys, flower pot saucers, swimming pool covers, etc.).
  • Apply an approved mosquito repellent with DEET to exposed skin and clothing.
  • Avoid going out at dawn and at dusk, when mosquitoes are most active.
  • Ensure rain barrels are covered at all times.

Officials test for West Nile on a weekly basis and they monitor natural and man-made standing water sites in Ottawa, such as ditches and storm water management ponds.

Larvicides are used when deemed appropriate in city-owned roadside storm sewers.

Last year in Ottawa, there were three probable human cases of West Nile.