The Wisconsin Department of Health Services (DHS) is advising residents to continue to protect themselves against mosquito bites as it announces this year’s first confirmed human case of West Nile virus (WNV) in a resident of Northeastern Wisconsin.

West Nile virus is spread to humans through the bite of an infected mosquito and is not spread person to person. Mosquitoes get the virus by feeding on infected birds.

The majority of human WNV cases occur during the months of August and September. However, the risk of contracting WNV and other mosquito-borne illnesses, such as Jamestown Canyon virus, La Crosse encephalitis virus, or eastern equine encephalitis virus, is present any time mosquitoes are active, so it is important for people to be vigilant about preventing mosquito bites throughout the rest of the summer and into early fall.

The chances of a person contracting WNV are very low, and most people infected with WNV will not get sick. Those who do become ill may develop a fever, headache, and rash that lasts a few days. Symptoms typically begin between three to 15 days after being bitten by an infected mosquito. In rare cases, WNV can cause severe disease with symptoms such as disorientation, tremors, paralysis, inflammation of the brain, and coma. Older adults and people with weakened immune systems are at an increased risk of severe disease from the virus.

There is no specific treatment for WNV other than to treat symptoms. If you think you have a WNV infection or another illness spread by mosquitoes, contact your health care provider. Although few mosquitoes actually carry the virus, there are several things you can do to reduce contact with mosquitoes and to get rid of areas where they breed.

DHS recommends the following:

  • Limit time spent outside at dawn and dusk, when mosquitoes are most active.
  • Apply an insect repellant with DEET, IR3535, picaridin, or oil of lemon eucalyptus to exposed skin and clothing.
  • Make sure window and door screens are intact to prevent mosquitoes from getting into your home.
  • Prevent mosquitoes from breeding by removing stagnant water from items around your property, such as tin cans, plastic containers, flower pots, discarded tires, roof gutters, and downspouts.
  • Turn over wheelbarrows, wading pools, boats, and canoes when not in use.
  • Change the water in bird baths and pet dishes at least every three days.
  • Clean and chlorinate swimming pools, outdoor saunas, and hot tubs; drain water from pool covers.
  • Landscape to prevent water from pooling in low-lying areas, and trim tall grass, weeds, and vines since mosquitoes use these areas to rest during hot daylight hours.

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