Measles Cases Explode From 2 to 15 in Southwestern Wisconsin With More Expected

A Sudden and Alarming Surge

What started as two confirmed measles cases in rural southwestern Wisconsin escalated dramatically within days. The number of measles cases in Iowa and Lafayette Counties jumped from two to 15 on August 14, state health officials confirmed. The Wisconsin Department of Health Services also reported six additional probable cases. Officials made clear this is almost certainly not the full picture.

"The rapid emergence of these cases, particularly among people who have not traveled outside of Wisconsin, indicates that there is active local transmission," said Ryan Westergaard, chief medical officer and state epidemiologist for communicable diseases for the Wisconsin DHS. "It is very likely that additional cases exist in the community that have not yet been identified or reported to public health." The 15 cases bring the total number of measles cases in Wisconsin to 17 in 2026.

Who Is Getting Sick — and Why It Matters

About 60% of cases were confirmed in children younger than 18 years old, and all but one case was confirmed in people who were unvaccinated. That pattern is stark. The cases are believed to have been exposed in Wisconsin, suggesting there may be additional measles cases in communities that have not yet been identified — and not everyone who becomes sick seeks medical care or is tested for measles, which means public health agencies may not be aware of every case in a community.

The outbreak comes on the heels of an executive order from President Donald Trump, which spaces out childhood vaccines. Wisconsin's top health official pushed back. DHS Secretary Kirsten Johnson released a statement saying the Wisconsin DHS "relies on systematic and transparent reviews of scientific evidence to inform any updates to immunization guidance." Wisconsin is not alone in its struggles against measles this year — the U.S. as a whole is having its worst year with the disease since 1991, according to the CDC, with the country approaching nearly 2,500 positive cases so far in 2026.

Why Measles Is So Dangerous

Measles is a highly contagious disease that can be spread from person to person through the air and can stay in the air for two hours after a sick person coughs or sneezes. It can cause serious health complications, including pneumonia, brain damage, and deafness, and can sometimes be deadly. These aren't abstract risks. One in four people who get measles in the United States will be hospitalized.

Symptoms can appear between 10 and 21 days after exposure. Those symptoms include runny nose, high fever, tiredness, cough, and red or watery eyes. Anyone suspecting they've been exposed should call a doctor before showing up to a clinic or emergency room — health officials ask that patients call ahead so staff can take precautions to prevent further spread.

What You Should Do Now

Two doses of the measles vaccine are 97% effective at preventing the disease, according to DHS. People born before 1957 are considered immune and do not need a vaccine. All other adults without laboratory evidence of immunity should have at least one dose of a measles-containing vaccine, and children should have two doses.

Residents can check their vaccination status through the Wisconsin Immunization Registry or by contacting their health care provider or local health department. Vaccines are available through health care providers, local clinics, and pharmacies. Free, confidential assistance finding a provider is available by dialing 211. With the outbreak still actively spreading and investigators still working to identify exposure locations, the window for getting ahead of this is narrow — and shrinking fast.