Editor's Note: A previous version of this story reported all Teton County three cases were in unvaccinated adults. The third is of an “unknown” vaccination status.
A third adult in Teton County has been diagnosed with measles, marking the first state’s first outbreak of 2026 and prompting the county to declare a “state of emergency.”
The cases are all linked via transmission, with the first case detected in someone who lives and works inside Grand Teton National Park (GTNP), where the National Park Service Office of Health and Safety is assisting in contact tracing. See below for a list of places where the public may have been exposed.
The first two cases were in unvaccinated adults and the third was an adult with an unknown vaccination status.
The first, second and third cases were confirmed on June 28, July 10 and July 11. All three lived in Colter Bay Village, where many employees of companies that run concessions for GTNP live in high-density housing. Park concession employees mixing with tourists in the popular hub make it a “particularly challenging location” for measles mitigation, according to a Teton County public health press release.
So far this year, the Wyoming Department of Health has reported four measles cases, the first in April in Fremont County with the rest in Teton County. Last year, the state reported 15 cases.
Measles is a highly contagious, airborne disease that can linger in the air for two hours. Symptoms typically develop between seven and 21 days after exposure and may include fever, cough, runny nose, red eyes and a rash.
The outbreak includes the county’s first case in at least 15 years and comes as the U.S. grapples with a broader 30-year high of measles cases, especially concentrated in Utah. It comes as Teton County, a gateway to Grand Teton and Yellowstone national parks, experiences one of its busiest periods of the year.
“As this outbreak unfolds, I suggest individuals confirm their own immunity status, or get
the MMR [measles, mumps, and rubella] vaccine if they cannot confirm it,” said Dr. Travis Riddell, the county’s public health director, in a press release.
A hospital spokesperson for St. John’s Health, the area’s largest healthcare provider, was not immediately available for comment.
State and local experts recommend vaccination. Two doses of the MMR vaccine is 97% effective, according to the U.S. Centers for Disease Control (CDC). Children, pregnant women and the immunocompromised, besides unvaccinated adults over 20, are at the most risk of developing severe complications or die due to measles, according to the CDC.
The county is asking the public to be vigilant for signs of the disease and contact medical help if they believe they have been exposed and are at high risk.
The public may have been exposed to measles at the following locations and times:
Annie’s Thai Kitchen
- 5 p.m. to 8 p.m. on July 4, 2026
Teton Village, Base of Jackson Hole Mountain Resort (July 4 fireworks event, outdoor exposures only)
- 6:30 p.m. to 11 p.m. on July 4, 2026,
Colter Bay Launderette and Showers, Grand Teton National Park
- 6:45 a.m. to 5:15 p.m. on July 5
- 6:45 a.m. to 5:15 p.m. on July 6
- 1:30 p.m. to 10:30 p.m. on July 7
Smith’s Food and Drug
- 11:30 a.m. to 1:30 p.m. on July 5
Wendy’s
- 12:15 p.m. to 2:15 p.m. on July 5, 2026,
Colter Bay General/Grocery Store, Coffee Bar, and Gift Shop, Grand Teton National Park
- 9 a.m. through 11 a.m. on July 7
Colter Bay Cabin Office, Grand Teton National Park
- 3 p.m. to midnight on July 7
