Michigan is reporting the state’s first measles outbreak since 2019, defined as at least three or more related cases, according to the Michigan Department of Health and Human Services (MDHHS). Three cases were confirmed in Montcalm County, according to a MDHHS statement. Almost 25% of children under 3 years of age in Montcalm County have not received their first dose of the measles, mumps and rubella (MMR) vaccine, according to the MDHHS vaccination data. The state is reporting a total of seven cases so far this year, including those infected in the outbreak.

Michigan’s first measles outbreak in more than five years has been reported in Montcalm County. The West Michigan county has confirmed its third related case of the year, qualifying it as an outbreak of the highly infectious virus, state health officials reported Thursday, April 17. Montcalm’s outbreak has been linked to a large, ongoing outbreak in Ontario, Canada. Ontario reported 109 new cases Thursday, bringing the province total to 925 cases, according to The Globe and Mail. The Montcalm cases are not believed to be related to Michigan’s other four confirmed cases, reported in Ingham, Kent, Macomb and Oakland counties.

An outbreak is defined as three or more related cases, which has been confirmed in Montcalm County, according to the Michigan Department of Health and Human Services and the Mid-Michigan District Health Department, which serves Clinton, Gratiot and Montcalm counties. “This outbreak underscores how contagious measles is and how quickly it can spread,” said Natasha Bagdasarian, the state's chief medical executive. The agencies said seven cases have now been confirmed across the state in 2025 — one each in Oakland, Kent, Macomb and Ingham counties — in addition to three in Montcalm County. Officials said the Montcalm cases are not related to any others across the state.

Montcalm County reports Michigan's first measles outbreak of 2025. There are currently seven confirmed cases of measles in Michigan in 2025. Some of the cases involved people who had traveled shortly before diagnosis. The MMR (measles, mumps and rubella) vaccine remains our best defense.

Michigan health officials have confirmed the state’s first measles outbreak of the year and its first outbreak of the highly contagious disease since 2019.