BOZEMAN — The number of measles cases in Montana is experiencing a slow increase, with the Montana Department of Public Health and Human Services reporting 11 known cases since April.

This uptick follows the first reported cases of measles in the state since the 1990s, which occurred in Gallatin County.

To date, Gallatin County has reported a total of nine cases, with the latest being an adult. Additionally, Flathead County in northwest Montana and Hill County on the Hi-Line have each confirmed one case of the highly infectious disease. Notably, the case in Hill County involves a child who was not vaccinated.

On May 12, the Gallatin City-County Health Department reported that 8 cases reported in April had recovered. At that time, all the cases in Gallatin County were isolated to household members.

According to the Gallatin City-County Health Department, as of May 22, 2025, a total of 1,046 confirmed measles cases have been reported across 31 jurisdictions: Alaska, Arkansas, California, Colorado, Florida, Georgia, Hawaii, Illinois, Indiana, Kansas, Kentucky, Louisiana, Maryland, Michigan, Minnesota, Missouri, Montana, New Jersey, New Mexico, New York City, New York State, North Dakota, Ohio, Oklahoma, Pennsylvania, Rhode Island, Tennessee, Texas, Vermont, Virginia, and Washington. There have been 14 outbreaks (defined as 3 or more related cases) reported in 2025, and 92% of confirmed cases (961 of 1,046) are outbreak-associated. For comparison, 16 outbreaks were reported during 2024, and 69% of cases (198 of 285) were outbreak-associated.

Health officials are urging residents to ensure they are fully vaccinated to help prevent further spread of the disease. Measles is highly contagious and can pose serious health risks.

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5 measles cases confirmed in Gallatin County, 1st in Montana since 1990