Measles cases confirmed in Wisconsin

The Wisconsin Department of Health Services along with Oconto County Public Health have confirmed nine cases of measles in Oconto County, Wisconsin, north of Green Bay.

One case was confirmed through testing at the Wisconsin State Laboratory of Hygiene, with eight other cases confirmed based on exposure and symptoms, DHS officials said in a statement.

All of those infected were exposed to a common source during out-of-state travel, according to the statement. No additional information will be released due to privacy laws, officials said.

DHS, in coordination with the Oconto County Public Health Department, is working to identify and notify people who may have been exposed to the measles virus. No public points of exposure have been identified and the risk to the community remains small, officials said.

The first case of measles in Dane County, Wisconsin, in more than two decades was confirmed in April 2024. A county resident who works in Rock County, Wisconsin, was infected while traveling domestically outside of Wisconsin, health officials said then.

Measles is a extremely contagious disease that can be spread through the air and can stay in the air for two hours after an infected person coughs or sneezes. It’s so contagious that if one person contracts it, as many as 90 percent of the people around them may also become infected if they are not vaccinated, DHS officials said.

Symptoms of measles include fever, cough, runny nose, pink eye and a telltale rash. They typically don’t develop until at least 10 days after exposure. People with measles remain infectious for about nine days.

Measles can cause serious health complications for those who aren’t vaccinated, DHS officials said. Cases of measles have been rare in Wisconsin because of relatively large vaccination rates historically, but only 84.8 percent of kindergartners in Wisconsin had received two doses of the vaccine in the 2023-2024 school year. That's the third-worst among states after Idaho and Alaska, the Centers for Disease Control and Prevention said in 2024.

The state’s relatively small rate “definitely makes us vulnerable,” said Dr. Jasmine Zapata, chief medical officer for community-health promotion at the Wisconsin Department of Health Services.

In the previous decade, Wisconsin had few cases. There were two in 2014. In 2021, there were 22 cases in an outbreak at Fort McCoy among people who had recently traveled from Afghanistan during the U.S. government’s emergency-evacuation efforts.

The best way to protect against measles is to get the Measles-Mumps-Ruebella or MMR vaccine, DHS officials said. Two doses of the measles vaccine are 97 percent effective at preventing the disease.