Public Advised of Possible Measles Exposure in Gallatin County

The Gallatin City-County Health Department (GCCHD) is advising the public of several potential exposure sites in Gallatin County from a recently confirmed measles case. A list of potential exposure sites – and recommendations for those exposed – is available on the GCCHD website and will be updated as new information becomes available. The times listed on the website include when the potential exposure occurred and two hours after.

The GCCHD confirmed an additional case of measles in Gallatin County on December 1, 2025. This follows a previous case confirmed on November 28, 2025. The latest confirmed case is believed to have been exposed at one of the previously identified public exposure sites. These sites, which date back to early November, were recently shared with the public as part of our ongoing eƯorts to notify those who may have been at risk, and to limit further spread of the virus.

Please note: If you were at any of the locations listed on November 28, please verify that you are immune to measles immediately. If you determine you do not have immunity to measles or are unsure, please call your primary care provider or the Gallatin City-County Health Department as soon as possible at 406-582-3100 and ask to speak to a Communicable Disease Specialist. You may be eligible for Post Exposure Prophylaxis in the form of the MMR vaccine if administered today, Monday December 1st, 2025 (within 3 days following exposure).

Measles can spread before symptoms appear—even before a rash is visible. The virus is highly contagious and can remain in the air for up to two hours after an infected person has left the area. This makes early exposure diƯicult to detect and increases the risk of transmission.

"With holiday activities and gatherings this month, it is especially important to know your vaccination status," said Lori Christenson, Gallatin City-County Health OƯicer. "We encourage everyone to take proactive steps by speaking with their health care provider about the MMR vaccine, which oƯers strong protection against measles. Informed decisions about vaccination are key to keeping our families and communities safe and healthy."

Vaccination is the best way to help prevent the spread of measles. Please contact your health care provider for more information. The MMR vaccine is 97% eƯective against preventing the spread of measles. Individuals without prior immunity to measles have a 90% chance of contracting the disease if exposed. If you are unsure of your immunity status, consult with a health care provider. Maintaining high vaccination rates within the community protects those who cannot be vaccinated.

Measles is a highly infectious airborne disease with initial symptoms including fever, cough, runny nose, red eyes, and white spots in the mouth, followed by a red rash that typically starts on the face and spreads downward. Measles infection can also result in serious complications, including pneumonia, brain swelling, and even death. It poses significant risks to infants, who are generally not eligible for vaccination until 12 months of age.

The GCCHD offers MMR vaccinations and encourages residents in need of the vaccine to contact their health care provider. We believe in working together to help you make the best choice for your health. For more information or to schedule an appointment, visit our website or call 406-582-3100.

All additional updates for measles information will be made available on our website unless the risk to public health changes.