A second mosquito pool in Lambton County has tested positive for the West Nile virus.
Lambton Public Health said on Monday that the mosquitoes were collected from a trap in Petrolia on August 19.
Another mosquito pool previously tested positive for the virus in Oil Springs on August 12.
While there have been no positive human cases of West Nile in Lambton County, two people have recently tested positive elsewhere in the province.
Mosquito samples are collected and tested weekly from pools across Lambton County.
The health unit is encouraging local residents to eliminate mosquito breeding sites by removing any pooling or standing water on their property. To reduce the risk of being bitten by mosquitoes, the health unit said residents should wear protective, light-coloured clothing and use repellents containing DEET or Icaridin.
The majority of people infected with West Nile virus do not get sick. Those who do become ill usually experience mild flu-like symptoms such as fever, headache, skin rash or muscle aches. Less than one per cent of people infected with the virus get seriously ill.
-With files from Dave Dentinger