It came to light after both people donated blood this week.

Manitoba Health is now probing when the people were infected, and if they previously donated blood while infected.

Both people live in the Winnipeg Health region and are in their 40s. They donated blood on Thursday and Friday, but a blood-screening test found that both blood samples were infected, the provincial government said.

Hot, humid weather has created ideal conditions for Culex tarsalis mosquitoes, the ones that carry West Nile Virus, to hatch, bite and transmit the virus.

There's a high risk of exposure throughout southern Manitoba.

Manitoba Health is not currently recommending an adult mosquito control program.