And they're already investigating a number of possible patients.
Phil Curry, an entomologist with the province's health ministry, isn't saying where the potential cases are. He noted investigators are still testing and checking details like whether the people travelled, or where they may have been infected by Culex tarsalis mosquitoes — the insects that carry the disease.
"The risk should be considered to be all through the agricultural zone of Saskatchewan. We've had Culex tarsalis reported from Estevan to Lloydminster to Melfort. So anywhere in the agricultural portion is considered to be at risk," said Curry.
Saskatchewan so far has one confirmed case of West Nile disease this year. Earlier this month, a Regina man found out he had the virus after screening that was done when he donated blood.
Curry said the cases that are currently under investigation may also have occurred earlier in the season and the patients are only just now suffering symptoms and seeking medical attention.
The risk of contracting the disease this year is still there, however, according to the Saskatoon Health Region.
The region issued a news release Friday announcing that mosquitoes carrying West Nile were caught in city traps for the first time in five years.
The samples were taken earlier this month but the region's deputy medical health officer said people should continue to take precautions against Culex tarsalis mosquitoes.
"Thankfully, the population numbers for this type of mosquito have been low this summer and will continue to decline over the coming weeks," Dr. Julie Kryzanowski said in the release.
"However, with the confirmation of the virus within this population and continued hot weather, we want to remind residents that it is very important they take protective measures," she added.
Ontario is reporting that as of earlier this week, 49 confirmed and probable human cases of the disease have been spotted. Alberta also announced this week that it has seen its first human case since 2010 in a woman from the southern part of the province.
Kryzanowski said no further mosquitoes in Saskatoon have tested positive for West Nile since the ones earlier this month. She said samples are sent to the province for testing every week.
U.S. authorities, meanwhile, said they've never seen as many cases of West Nile infection as early in the year as they are seeing in 2012.
Officials have cited the mild winter, early spring and hot summer in parts of the country as causes.
There have been over 1,100 human cases in the United States this year, including 41 deaths.