BOZEMAN — The Gallatin City-County Health Department (GCCHD) announced two additional confirmed cases of measles in Gallatin County. The first case, involving an adult, was reported on May 23, 2025. The individual was hospitalized but has since been released, with the hospital implementing necessary precautions for isolation during treatment. The second case, also involving an adult, was confirmed on May 28, 2025. The vaccination status of the first individual is unknown, while the second is fully vaccinated.

This brings the total number of confirmed measles cases in Gallatin County to 10.

According to GCCHD, five cases were reported on April 17, exposure was determined to be from out-of-state travel. On April 29th, 2 more cases were confirmed, household exposure from the previous case. On May 5th, another case was confirmed, also from household exposure to the prior case.

The health department has not yet identified the exact source of exposure for the cases, but preliminary investigations suggest that both individuals were likely exposed around the same time and had no reported contact with previous cases, nor had they traveled or had visitors. GCCHD is actively investigating the initial source.

GCCHD has identified the potential public exposure site, as Casey's Corner, 4135 Valley Commons Dr. in Bozeman, from 7 to 10 am. The health department cautions that measles can be transmitted before symptoms appear, including before a rash develops. The exposure times listed on the website include the period of exposure and two hours following it.

"With summer approaching and families preparing to travel—whether within Gallatin County or to destinations elsewhere—measles remains a concern for our community," said Lori Christenson, Gallatin City-County Health Officer. "We encourage everyone to take proactive steps by consulting their health care provider about the MMR vaccine, which provides strong protection against measles. Making informed decisions about vaccination is essential to keeping our families and communities healthy."

The routine MMR vaccination schedule remains in place in Gallatin County, and individuals are urged to contact their healthcare provider for more information. The MMR vaccine is 97% effective against measles, but persons without prior immunity have a 90% chance of contracting the disease if exposed.

Measles is a highly infectious airborne disease. Its initial symptoms include fever, cough, runny nose, red eyes, and white spots in the mouth, followed by a red rash that typically begins on the face. Complications can include pneumonia, brain swelling, and even death, particularly threatening to infants who cannot be vaccinated until 12 months of age.

Symptoms of measles typically develop 7 to 14 days after exposure but can take up to 21 days to appear. A rash usually develops 2 to 4 days after the initial symptoms and typically lasts 5 to 6 days. Individuals with measles are considered infectious for a total of 9 days, beginning 4 full days before the rash appears and continuing through 4 full days after rash onset.

GCCHD provides MMR vaccinations and encourages residents to reach out to their healthcare provider or local pharmacy for vaccination needs. For more information or to schedule an appointment, visit the GCCHD website or call 406-582-3100.

Updates regarding measles will be available on the GCCHD website unless there are changes to the risk level for public health.

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