CHEYENNE — Wyoming has recorded its first measles of the year.

The Wyoming Department of Health reports the case was discovered in a Fremont County adult who has an unconfirmed vaccination status. Measles is highly contagious, especially to infants, nonimmune pregnant women, and people who have compromised immune systems. The infection can cause serious illness and everyone exposed to measles has a risk of infection. In 2025, 15 cases were reported throughout the state.

The department said people who were at the Riverton Walmart from 6:30-9 p.m. on April 24 and the Maverik at 819 E. Coulter Ave. in Powell on April 25 from 10:45 a.m. to 1 p.m. may have been exposed to the virus. The virus can remain in the air for two hours after an infected person leaves an area. 

“We are asking individuals who were potentially exposed to self-monitor for measles symptoms for 21 days past the exposure date, and consider avoiding crowded public places or high-risk settings such as daycare centers,” Dr. Alexia Harrist, the state health officer with the WDH said.

People can develop symptoms between seven and 21 days after being exposed to measles and include cough, runny nose, fever, red eyes, and a rash that begins on the face and spreads downward. People who develop these symptoms are encouraged to contact their medical provider, emergency room or urgent care by phone to prevent additional exposures. People who have received the MMR vaccine or were born before 1957 are generally considered immune and are unlikely to develop measles.

“Measles is one of the most contagious diseases we know, but it is preventable,” Dr. Harrist said. “The MMR vaccine is safe and highly effective, providing long-lasting protection. Two doses of MMR vaccine are about 97% effective in preventing measles, and we recommend that all Wyoming residents ensure they and their children are up to date on MMR vaccinations.”