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West Nile Virus

West Nile virus is an illness spread by the bite of an infected mosquito. The type of mosquitoes that spread West Nile virus can be found in every county in Wisconsin. Not all mosquito bites will make you sick, but it is still important to take steps to protect yourself and your family while enjoying time outdoors. West Nile virus is preventable.

Learn general information about West Nile virus, including information on signs and symptoms, treatment, and resources.

Explore our maps and charts with West Nile virus data.


This page is for local health departments, health care providers, or those looking for information on reporting, surveillance, or diagnosis of West Nile virus.

Get tips on preventing mosquito bites.

Questions about illnesses spread by mosquitoes? Contact us!
Phone: 608-267-9003 | Fax: 608-261-4976

Last revised June 15, 2022