Southwest Wisconsin measles outbreak spread escalates

The measles outbreak reported earlier this month in Southwest Wisconsin has increased markedly this week, the state health department reported Friday.

With newly identified cases, the total number of people in Grant, Iowa and Lafayette counties confirmed with the viral illness has increased to 92, according to the Wisconsin Department of Health Services. Another six people have been identified as probably having measles.

In addition to those 98 patients, two other people in Wisconsin were diagnosed with measles at the beginning of 2026. All but one of the 100 Wisconsinites with confirmed or probable measles this year had not been vaccinated, according to DHS.

Of all Wisconsin measles patients this year, 40% are 18 years old or older, 46% are 5 to 17 years old and 14% are age 4 or younger, according to DHS. The department doesn’t publish the demographic information for specific outbreaks.

So far the Southwest Wisconsin outbreak has not been spreading through general public exposure, according to DHS.

“There’s ongoing transmission of disease from previously identified cases,” said Dr. Stephanie Schauer, DHS immunization program manager, in a video recorded by the department Friday. “So this speaks to the very infectious nature of measles.”

Nine out of 10 people who are susceptible to measles and exposed to someone with the virus, such as a family member or a person they live with, will come down with the illness, she said.

“So if one person in that household becomes sick with measles, and then they expose others in that household, those others are likely to become sick about 10 to 14 days later,” Schauer said.

The measles vaccine — typically delivered in combination with mumps and rubella vaccines — remains the best prevention from the virus, Schauer said.

Earlier this week the Centers for Disease Control reported 2,777 measles cases nationwide. The first two deaths from measles in the U.S. this year were confirmed this week in Pennsylvania, the Pennsylvania Capital-Star reported.