West Nile virus cases increasing in Minnesota

News Release
Aug. 26, 2025

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The Minnesota Department of Health (MDH) has reported 20 cases of West Nile virus so far in 2025. Two of the affected people have died. Case numbers can vary significantly from year to year due to factors like heat and rainfall, but the recent increase has health officials encouraging people to take precautions.

West Nile virus is transmitted to people through the bite of an infected mosquito. Most people who are bitten by infected mosquitoes will experience either no symptoms or a mild flu-like illness. Less than 1% of people who are infected develop encephalitis or meningitis (inflammation of the brain or surrounding tissues). Symptoms usually show up within one to two weeks. There is no treatment for the illness other than supportive care.

Elderly patients and those with weakened immune systems are at greatest risk for severe disease, followed by people who work outside or participate in outdoor activities.

In Minnesota, cases of West Nile virus disease have been found throughout the state. The highest risk areas for West Nile virus include the agricultural regions of western and central Minnesota. Nationally, other states in the western and central U.S., including Iowa, North and South Dakota, are also seeing increased activity.  

“This is a high-risk time of year for West Nile virus transmission,” said Elizabeth Schiffman, supervisor of MDH’s Vectorborne Diseases Unit. “It’s important to prevent mosquito bites when people are enjoying time outside while the weather is still nice. That’s the best way to avoid getting West Nile virus.”

To protect yourself and your family from mosquito bites:

• Use insect repellents that are registered by the Environmental Protection Agency and contain up to 30% DEET.  
• Pretreat clothing and gear with permethrin-based products.  
• Wear loose-fitting, long-sleeved shirts and pants.  
• Be extra cautious or avoid outdoor activities at dusk and dawn, the peak feeding time for many mosquitoes, particularly from July through September.
• Keep mosquitoes out of your home by maintaining screens on windows and doors.

More information about West Nile virus can be found on the MDH website at West Nile Virus. 

-MDH-

Media inquiries:
Amy Barrett
MDH Communications 
651-201-4993
amy.barrett@state.mn.us