Risk of mosquito-borne West Nile virus is increasing amid a hot and rainy summer season, the Minnesota Department of Health warned this week.
The state so far has confirmed 20 cases, including two deaths, which occur when the infection causes encephalitis or meningitis — swelling of the brain or surrounding tissue.
While those numbers aren’t unprecedented in Minnesota, people should take precautions at this “high-risk time of year,” said Elizabeth Schiffman, supervisor of the state Health Department’s vectorborne diseases unit.
“It’s important to prevent mosquito bites when people are enjoying time outside while the weather is still nice,” she said. “That’s the best way to avoid getting West Nile virus.”
Risks appear greatest right now in western and central agricultural regions of the state, breeding grounds for the Culex tarsalis mosquito that is the primary spreader of the virus.
About 1 in 5 infected people will endure symptoms such as headache or fever and 1 in 150 will suffer severe complications, according to the Health Department. Risk of severe illness is greatest among the elderly and people with weakened immune systems.
West Nile was first detected in Minnesota in 2002 and caused a record 148 confirmed infections in 2003. The state recorded 35 cases and one death last year, and 63 cases and four deaths in 2023.
