Montana Experiences First Measles Outbreak in Decades
Montana has recently confirmed five cases of measles, marking the state as the ninth in the U.S. to report an ongoing outbreak. Health officials announced these cases last Thursday, noting that they involved unvaccinated individuals who had traveled to areas affected by the virus.
Details of the Outbreak
The confirmed cases are clustered in the Bozeman and Belgrade areas and are the first instances of measles within Montana in 35 years. The official confirmation came on the following Monday after the initial announcement, sparking concern among health authorities.
Measles Outbreaks Nationwide
As of now, concomitant outbreaks of measles are affecting several states across the U.S. Including Texas, Kansas, Oklahoma, Ohio, Indiana, Pennsylvania, Michigan, and now Montana. In total, there have been 800 reported cases observed in 2025, with more than 10 clusters involving three or more related infections.
Current Case Counts by State:
- Texas: 597 cases
- Kansas: 37 cases
- Oklahoma: 12 cases
- Ohio: 30 cases
- Indiana: 8 cases
- Pennsylvania: 9 cases
- Michigan: 7 cases
Broader Context in North America
The situation is not limited to the U.S.; Ontario, Canada, is grappling with a significant outbreak that has affected 925 people from mid-October through April 16. Moreover, the World Health Organization linked cases in Mexico to the ongoing Texas outbreak, where Chihuahua has reported 433 cases as of April 18.
Understanding Measles and Its Risks
Measles is an extremely contagious virus that can linger in the air for up to two hours. The Centers for Disease Control and Prevention (CDC) highlights that approximately 90% of unvaccinated individuals exposed to the virus will contract it. Historically, prior to the introduction of the measles vaccine in 1963, the United States witnessed between 3 to 4 million cases annually. However, typical annual cases have now dropped to fewer than 200.
Measles was officially declared eliminated from the U.S. in the year 2000, making recent outbreaks particularly concerning.
Preventive Measures and Vaccination
Vaccination remains the most effective means of preventing measles. The CDC recommends administering the measles, mumps, and rubella (MMR) vaccine in two doses: the first between 12 and 15 months, and the second between 4 and 6 years. There is no harm in receiving an additional dose if there are concerns about waning immunity.
Individuals with vaccination records from the 1960s do not necessarily need to be revaccinated; however, those who received the earlier “killed” virus vaccine prior to 1968 are advised to get at least one dose of the live vaccine. Generally, those born before 1957 are considered to have “presumptive immunity” owing to past exposure to measles.
Communities that maintain high vaccination rates—95% or above—can achieve what is termed “herd immunity,” which significantly reduces the likelihood of the virus spreading.
Conclusion
The resurgence of measles in Montana and other states underscores the critical importance of vaccination in preventing outbreaks. This situation serves as a reminder of the necessity for public health vigilance and community cooperation in maintaining immunity against preventable diseases.
FILE – A health care worker fills a syringe with the MMR vaccine, at a vaccination clinic organized by Lubbock Public Health Department on March 1, 2025 in Lubbock, Texas. (Photo by Jan Sonnenmair/Getty Images)