Wisconsin measles outbreak hits southwestern counties

A measles outbreak is spreading through southwestern Wisconsin, with the Department of Health Services reporting 41 confirmed cases and seven probable cases. The infections are distributed across Iowa, Lafayette, and Grant counties, with the majority of confirmed cases located in Iowa County.

Health officials attribute the spread to low vaccination rates in specific communities. Data indicates that nearly all individuals infected in Wisconsin this year have been unvaccinated. The outbreak affects a range of ages, with just over half of the cases occurring in children and teenagers, while 44% are among adults.

In some areas, immunization coverage is significantly below the 95% threshold required to prevent outbreaks. For instance, in 2025, only 60% of two-year-olds in Lafayette County and approximately 64% in Grant County had received the necessary vaccine series. Officials note that while pandemic-related vaccine skepticism has impacted rates, some communities saw declining uptake prior to COVID-19.