• Nine measles cases confirmed in Williams County, North Dakota, all in unvaccinated individuals.
• The outbreak marks the first measles cases in North Dakota since 2011, with possible community transmission identified.
• Health officials urge vaccination and monitoring for symptoms, especially for those exposed at schools and a Walmart.

An outbreak of measles has been reported in Williams County, North Dakota, with nine confirmed cases as of May 6, 2025. All identified individuals were unvaccinated. The first case, detected on May 2, was an unvaccinated child believed to have contracted the disease from an out-of-state visitor. Health officials have identified potential exposure sites, including Williston schools and a local Walmart, prompting recommendations for vaccination and symptom monitoring. This outbreak marks the first occurrence of measles in North Dakota since 2011.

• What: A measles outbreak with nine confirmed cases in Williams County, North Dakota, primarily affecting unvaccinated individuals. The virus is spreading, leading to potential community transmission and exposures in schools and public places.
• Who: Affected individuals are primarily unvaccinated residents of Williams County, North Dakota. Key organizations involved include North Dakota Health and Human Services, Upper Missouri District Health Unit, and the Centers for Disease Control and Prevention (CDC).
• When: The outbreak began in early May 2025. The first case was identified on May 2. Potential exposures occurred at Williston Walmart on April 29 between 2 and 5 p.m. School exclusions are in effect from May 7 to May 21/23.
• Where: The outbreak is concentrated in Williams County, North Dakota, specifically in Williston. Exposure locations include Missouri Ridge Elementary, Williston Middle School, Williston High School, and the Williston Walmart.

The measles outbreak in North Dakota highlights the risks associated with declining vaccination rates. The fact that all identified cases are among unvaccinated individuals underscores the importance of the MMR vaccine in preventing the spread of this highly contagious disease. The identification of potential exposure sites in schools and a Walmart suggests the possibility of community transmission, requiring swift and comprehensive public health interventions to contain the outbreak. The outbreak also comes amid rising measles cases nationwide, emphasizing the interconnectedness of public health and the need for coordinated efforts to maintain high vaccination coverage.

Due to the current measles outbreak, please isolate at home if you have symptoms of runny nose, fever, cough, and rash. Isolation should continue until at least four full days after the onset of a rash. Time from exposure to onset of rash is generally around seven to 21 days, and you can spread measles up to four days prior to the time the rash appears.

The measles outbreak in North Dakota, with nine confirmed cases amongst unvaccinated individuals and potential community transmission evident by new cases not linked to previous ones, underscores the critical role of vaccination in preventing the spread of this highly contagious disease. With exposures occurring at schools and a Walmart, the state is implementing isolation measures and school exclusions for unvaccinated students and staff to contain the outbreak, which is the first in North Dakota since 2011. This situation is especially concerning given a backdrop of rising measles cases nationally, with 935 cases reported across 29 US states as of May 2025 and 3 confirmed deaths. The majority of these cases are among those unvaccinated or with unknown vaccination status, highlighting declining MMR vaccination coverage among kindergarteners and the risks associated with international travel and spread within unvaccinated communities. Ongoing surveillance, robust public health efforts, and increased vaccination rates are essential not only to prevent further spread in North Dakota but also to address the broader national resurgence of measles and protect vulnerable populations from severe complications, including hospitalization, brain swelling, and death.