After confirming a case of measles in an unvaccinated adult in Teton County, Wyoming health officials are warning the public about possible exposure at locations in Grand Teton National Park and Jackson. 

The news comes as summer crowds flood the region with tourists from around the world. 

The public may have been exposed between June 17-25 at several locations in Teton County, according to the Wyoming Health Department. They include restaurants in Grand Teton National Park’s Colter Bay Village on June 17-18; a Colter Bay convenience store on June 20 and the Target in Jackson on June 25. 

“We are asking people who may have been exposed to watch for measles symptoms for 21 days past the exposure date and consider avoiding crowded public places and high-risk settings such as daycare centers,” State Health Officer Alexia Harrist said in a press release. 

Monitoring is especially critical for people who have not been vaccinated with the measles, mumps, and rubella vaccine, according to the health department. 

It marks Wyoming’s second confirmed case of the highly contagious infection in 2026. Wyoming went 15 years without a confirmed case of measles until last year.

Resurgence 

Health officials confirmed Wyoming’s first 2026 case in May. An adult patient in Fremont County who did not have a confirmed vaccination status caught the disease, according to the Wyoming Department of Health. 

Measles was declared eliminated in the U.S. in 2000 — indicating no endemic transmission for 12 months or more. But it re-emerged in recent years primarily due to declining vaccination rates and increased public health skepticism. Those trends spawned during the COVID-19 pandemic and have persisted during the second Trump administration. 

The neighboring state of Utah is one of America’s 2026 measles hotspots, with 499 cases reported so far this year. 

Daren Chandler holds his 12-month-old daughter as she has blood drawn for testing, before receiving a measles shot at Tiger Pediatrics in Easley, S.C., on March 17, 2026. (AP Photo/Mary Conlon)

A vaccination rate of 95% is necessary for community immunity to prevent measles outbreaks, according to the Centers for Disease Control. 

In 2025, Wyoming’s proportion of kindergarten students who had completed the MMR vaccine was 93.6%, the CDC reports. That rate is higher than Colorado, Utah and Montana for the same year. 

However, it’s declined overall since 2012-13, when Wyoming’s kindergarten vaccination rate was above 97%. It fell to 90.2% in 2020-21 before inching back up to the current 93.6%. 

A measles case had not been reported in the state since 2010 until July 2025, when the health department confirmed measles in an unvaccinated child from Natrona County. By year’s end, 13 more cases were confirmed. The majority involved unvaccinated children and adults.  

Along with being extremely contagious, measles can cause severe complications like pneumonia and brain swelling and can leave lasting impacts on the immune system. One to three out of every 1,000 children who become infected with measles will die from complications, according to the CDC.

Katie Klingsporn reports on outdoor recreation, public lands, education and general news for WyoFile. She’s been a journalist and editor covering the American West for 20 years. Her freelance work has...

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