MADISON, WI — Wisconsin’s measles outbreak in the southwest part of the state has grown to 98 reported cases, according to the Wisconsin Department of Health Services. State officials said they confirmed 22 additional cases this week, bringing the total higher across Grant, Iowa and Lafayette counties.
The state count includes six probable cases. All but three of the reported cases are in Iowa and Lafayette counties, and nearly every case has been in someone who was not vaccinated. Health officials said most of the people affected are children.
State Case Count
DHS said the outbreak began with two cases reported on Aug. 11 and has expanded quickly since then. The department said transmission has stayed tied to people connected with previously identified cases, rather than showing broad new spread across the state.
Officials also said the rise in reported infections does not “necessarily indicate an increase in exposure risk to the broader public.” That distinction matters because the outbreak has been concentrated in communities where vaccination rates are lower, according to state health officials.
Vaccination Pattern
State officials said all but one of the reported cases are in people who were unvaccinated. They described the outbreak as concentrated in places with low vaccination coverage, which has helped the virus spread among linked contacts in the affected counties.
New data from the U.S. Centers for Disease Control and Prevention also showed Wisconsin had low measles vaccination rates among kindergarten students. The CDC estimated that 85.1 percent of Wisconsin kindergarten students had MMR vaccine coverage during the 2025-2026 school year.
What Officials Warn
Measles spreads through the air and can remain there for hours after an infected person coughs or sneezes, health officials say. The disease can lead to serious complications, including pneumonia and brain damage, and it can be fatal.
For now, the Wisconsin Department of Health Services is the main agency tracking the outbreak and updating the case count. Residents seeking the latest public health information can check DHS updates and CDC vaccination data as the situation develops.
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