A mosquito in Mitchell, Ont. has tested positive for West Nile Virus — the first this season in Perth County.

"West Nile virus activity has been low so far across Ontario, but it's not surprising to see activity begin to increase as historically we get positive mosquito pools around this time," public health inspector Stephanie Carlisle said in a news release Wednesday.

The health unit has been setting traps for mosquitoes since June. They have also applied larvicide to reduce breeding in Stratford, St. Marys, Listowel and Mitchell.

So far this year there have been four "probably or confirmed" cases of West Nile in humans in Ontario.

Not everyone who gets bitten by an infected mosquito will show symptoms. Those who do show symptoms may experience fever, headaches, body aches, nausea, vomiting and rashes on chest, stomach or back.

The health unit says you can protect yourself by using DEET or Icaridin insect repellent when outdoors, and also remove standing water around your home at least once a week to reduce breeding grounds for mosquitoes.