The Wyoming Department of Health on Monday announced an outbreak of measles in Teton County amid a heavy influx of summer visitors. 

The department declared the outbreak after confirming a third case of the highly infectious illness in Teton County this summer. The public may have been exposed at several locations in Jackson and neighboring Grand Teton National Park.

A baby with the measles. (Jim Goodson/CDC/Wikimedia Commons)

Health officials are asking people who may have been exposed to monitor themselves carefully for three weeks. Those who develop symptoms should call their doctor before seeking care to minimize exposure to others. 

Measles was declared eliminated in the U.S. in 2000 but has surged back in recent years with rising skepticism of public health officials and vaccinations. Wyoming went 15 years without a reported case until July 2025.

Potential exposures

When the first Teton County case was reported June 28, officials announced that exposure to the unvaccinated adult patient may have occurred at 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. 

On Saturday, the health department confirmed the county’s second case, followed by the third on Monday. 

An outbreak is defined by a “chain of transmission involving three or more confirmed or probable cases that are epidemiologically linked,” according to Wyoming Department of Health Chief Policy and Communications Officer Monique McBride. This means Teton County’s cases are related to one another in time and location, she told WyoFile in an email.  

Exposures to the two more recent cases could have taken place between July 4-7 at the following locations:  

  • Teton Village during the Fourth of July fireworks
  • Annie’s Thai Kitchen in Jackson
  • Wendy’s restaurant in Jackson
  • Colter Bay Launderette and Showers, Grand Teton National Park
  • Colter Bay General Store, Coffee Bar and Gift Shop, Grand Teton National Park
  • Colter Bay Cabin Office, Grand Teton National Park

Millions of people visit Jackson and nearby Grand Teton National Park each summer, crowding the town square, filling up parking lots and queueing up for popular attractions. 

Rising numbers

Wyoming’s measles outbreak comes as cases climb across the nation. When U.S. health officials declared measles eliminated in 2000, that indicated no endemic transmission for 12 months or more. 

In 2020, 13 cases were confirmed across the country, according to the Centers for Disease Control. In 2025, that number jumped to 2,289, including three deaths. The 2026 tally sits at more than 2,231 with no deaths.

Measles cases are growing in the United States. (Johns Hopkins University)

In 2025, Wyoming’s proportion of kindergarten students who had completed the measles, mumps, rubella vaccine was 93.6%, the CDC reports. It’s declined since 2012-13, when Wyoming’s kindergarten vaccination rate was above 97%.

The state’s first case in 15 years was confirmed in July 2025 in Natrona County. By year’s end, 13 more cases were confirmed. 

Wyoming’s first case of 2026 was detected in Fremont County.

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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  1. The increase in diseases like measles is no surprise. Both political parties share some blame for this. The skepticism, distrust, and misinformation about immunizations has been spread primarily by members of the Republican Party. It is primarily the Democratic Party that allowed millions of illegal immigrants, many from 3rd world countries where immunizations are far less common, into the country – and of course, unlike legal immigration which requires immunizations including measles, there is zero immunization vetting with illegal immigration. This fact is unpopular with left-leaning organizations and often not mentioned. However, it is primarily the Republicans cutting foreign aid, which includes vaccinations. It’s a vicious cycle.

    Reply
    1. Reply

    2. Thank you Bill, that hit the nail on the head.

      I see there are now 5 cases as of this morning.

      Measles vaccines are low cost or sometimes free at most public health offices. It’s easy to get vaccinated. I have little sympathy for adults who choose to remain unvaccinated, and it is scary and heartbreaking to see the risk they are placing on members of my family and our society who are especially vulnerable. Babies less than 6 months old are too young for vaccination, but measles is especially devastating to them, sometimes leading to permanent brain damage, hearing loss, pneumonia, or death.

      Reply

    3. Vicious cycle indeed. Not a single Democrat would have taken the covid shot if it were Trump shoving it down americas throat instead of Biden.

      Laughable the getting a vaccination has been reduced to partisan litmus tests.
      Doesn’t help that our modern American Medical Industrial Complex is as trustworthy as a compulsive liar.

      Reply