BOZEMAN — A 12th case of measles has been confirmed in Gallatin County, according to the Gallatin City-County Health Department.

The case was community-acquired - the person had no reported contact with previous cases, no travel or visitors.

The case was confirmed on Monday, June 9. DPHHS is reporting that newly identified cases are isolating.

On Friday, officials confirmed the 11th case, which was a "known exposure from a previous case."

From the department listed the active exposure points are listed as:

• 6/3/2025 Ramirez Mexican Food - 319 No. 7th Ave. Bozeman - Monitor for symptoms through June 24, 2025
• 6/3/2025 On Mission Thrift - 425 No. 7th Ave. Bozeman - Monitor for symptoms through June 24, 2025
• 6/3/2025 Cash 4 Clothes - 119 No. 7th Ave - Monitor for symptoms through June 24, 2025
• 6/2/2025 Town & Country - 1611 So. 11th Ave. Bozeman - Monitor for symptoms through June 24, 2025
• 6/1/2025 Ace Hardware - 26 E. Main St., Bozeman - Monitor for symptoms through June 24, 2025

There are 20 total cases of measles in the state, according to the Montana Department of Health and Human Services. The 20 cases have been reported from the following jurisdictions in Montana: Flathead (2), Yellowstone (2), Hill (4), and Gallatin (12).

Measles has also been reported in surrounding states and provinces:

Measles is highly contagious, spreading rapidly among those without immunity. According to the Montana Department of Health & Human Services (DPHHS), “If somebody with measles walks into a room, 90% of people who have no immunity to it will get infected.”

Vaccination remains the most effective defense. One dose of the measles vaccine is about 93% effective, while two doses reach approximately 97% efficacy. Health officials warn that a recent decline in vaccination rates is largely responsible for the current outbreak.