The Wyoming Department of Health has found its first case of “community spread” measles in Teton County. The fourth case is in an adult.
This breaks the previous pattern seen in the first three cases over the last three weeks that were all linked via transmission to an outbreak in Colter Bay Village.
The fourth case may have exposed others from 7 a.m. to 7 p.m. on July 5, 6, and 7 at Target in Jackson.
A fifth case in Teton County, also announced Tuesday, was connected to the previous cases.
See below for a full 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 health department did not state the vaccination status of the fourth county case in its Tuesday press release.
“The virus is now moving locally in ways we can’t fully trace, which likely means there’s more measles circulating in Teton County than our confirmed case count reflects,” said a Teton County Health social media post on Tuesday.
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 highest risk of developing severe complications or dying due to measles, according to the CDC.
Dr. Travis Riddell, Teton County Public Health director, said if people are symptomatic, the county requests they isolate. He also recommends people quarantine if they are not symptomatic but have been exposed and lack immunity. He recommends people check their vaccination status with the state records where they may have been vaccinated or simply get the vaccine again.
“If you're not sure and you're able to confirm [your status], you can always get a vaccine. There's not really any downside to that,” he told KHOL.
After the discovery of a fourth county case on Monday, the county declared a local “emergency” to free up additional resources and signal a departure from day-to-day operations.
So far this year, the Wyoming Department of Health has reported five measles cases, the first in April in Fremont County. The rest were in Teton County. The first, second and third cases were confirmed on June 28, July 10 and July 11. All three lived in Colter Bay Village, where employees of companies that run concessions for Grand Teton National Park 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.
Last year, the state reported 15 cases, including its first in 15 years.
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 county and hospital are in close communication to prepare for the impacts of a larger outbreak.
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. to 11 a.m. on July 7
Colter Bay Cabin Office, Grand Teton National Park
- 3 p.m. to midnight on July 7
Target Jackson Hole
- 7 a.m. to 7 p.m. on July 5, 6 and 7
