West Nile virus shows up in Wisconsin for the first time this year

Minnesota has already had 3 cases.

This year’s first confirmed human cases of West Nile virus in Wisconsin have been reported.

The virus was found in residents of Oconto and Fond du Lac counties, a news release from the Wisconsin Department of Health Services says.

The disease is carried by a certain breed of mosquito, and it's around this time of the year (August and September) that West Nile cases begin popping up.

Contracting West Nile is pretty rare, the department says, and most people who get infected won't have any symptoms because their immune systems fight it off. But some cases can be severe or life-threatening.

That's why health officials are warning people to take "vigilant" protective measures to prevent mosquito bites.

Prevalence in Minnesota

The virus was first found in Minnesota in 2002, and is now the most commonly reported mosquito-borne disease in the state, the Minnesota Department of Health says

As of Aug. 15 of this year, 209 Americans had been infected with the virus, including three Minnesotans, according to this chart from the Centers for Disease Control and Prevention (CDC).

One of those Minnesotans developed a more severe, neuroinvasive case, the CDC says. In severe cases, West Nile virus can cause encephalitis (swelling of the brain) or meningitis. 

The western and central portions of Minnesota are the highest risk areas in the state. That's because open areas – like farms and prairies – provide the best habitat for Culex tarsalis, the mosquito that spreads the virus.

The worst year for West Nile virus in Minnesota was 2003, which saw 148 cases.


The virus is spread to people through the bite of an infected mosquito and is not transmitted person to person.

People who become ill usually start showing flu-like symptoms 3-15 days after being bitten. They may also develop a rash that lasts a few days. 

In rare cases, it can cause muscle weakness, stiff neck, disorientation, tremors, convulsions, paralysis, coma, or even death.

Older adults and people with compromised immune systems are at an increased risk of severe disease from the virus. 

And there's no "cure" or specific treatment for it, other than to treat symptoms.

Tips to minimize exposure

The Metropolitan Mosquito Control District offers these tips to minimize your exposure to mosquitoes:

  • Empty water-holding containers in yards or neighborhoods (where mosquitoes can breed).
  • Ensure window screens are in good shape.
  • Wear long-sleeved, loose-fitting, light-colored clothing outside.
  • Use bug spray.
  • Avoid prolonged outdoor activity at dawn and dusk – when mosquitoes are most active.

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