Paula Tran, State Health Officer and Administrator of the Division of Public Health | Wisconsin Department of Health Services
Paula Tran, State Health Officer and Administrator of the Division of Public Health | Wisconsin Department of Health Services
The Wisconsin Department of Health Services (DHS) has confirmed the first West Nile virus activity in the state for 2025. A resident of Barron County has been diagnosed with a human case of West Nile virus (WNV), and mosquitoes collected from Milwaukee and Lafayette Counties have tested positive for the virus.
"The first detections of West Nile virus this year are a reminder to take steps to prevent mosquito bites and possible disease. West Nile virus poses a risk to all Wisconsinites, but people who have weakened immune systems are at higher risk for serious illness," said Paula Tran, State Health Officer and Administrator of the Division of Public Health.
West Nile virus is transmitted to humans, birds, and other animals through the bite of an infected mosquito. Mosquitoes become infected after feeding on birds carrying the virus. The disease does not spread directly between people or between animals and people.
Most individuals infected with WNV do not show symptoms. Those who develop symptoms may experience fever, chills, headache, muscle aches, rash, and fatigue. Severe cases can include high fever, muscle weakness, stiff neck, disorientation, mental confusion, tremors, paralysis, seizure, and coma. Older adults and those with compromised immune systems face a higher risk of severe illness that can be fatal. DHS advises anyone suspecting they have WNV illness to contact a health care provider.
Since 2001, DHS has tracked confirmed cases of WNV in mosquitoes, animals, and humans across Wisconsin to inform both health care providers and residents about potential risks. On average each year in Wisconsin there are about 18 reported cases among residents. Human cases have occurred from June through November; most illnesses are reported in August and September.
To reduce the chance of infection from mosquitoes during summer months—when risk continues until a hard frost—DHS recommends minimizing exposure to mosquitoes and removing standing water where they breed. More information on prevention methods is available on the DHS website: https://www.dhs.wisconsin.gov/mosquito/prevention.htm
For further details about symptoms or prevention strategies related to West Nile virus (WNV), visit: https://www.dhs.wisconsin.gov/mosquito/wnv.htm
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