The Wyoming Department of Health reported a positive measles case in an unvaccinated adult in Teton County.
The person lives and works inside Grand Teton National Park. Following a Thursday hospital discharge, that person is safe and recovering in isolation, said Teton County Public Health Director Dr. Travis Riddell.
The person may have exposed others to the sickness at a few places in Grand Teton National Park: between noon and 10 p.m. on June 17 or 18 at Cafe Court Pizzeria and Ranch House Restaurant in Colter Bay Village and between 2 p.m. and 4 p.m. on June 20 at the Colter Bay Convenience Store. They also may have exposed others at Target in Jackson on the morning of June 25.
The highly contagious infection can linger in the air for up to two hours after the infected person leaves. Symptoms include a rash spreading down the body, a fever, cough, or runny nose. Anyone who was exposed is at risk of contracting measles, which is one of the most infectious diseases known. It can be life-threatening for infants, pregnant people and the immunocompromised.
“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 Dr. Alexia Harrist said in a press release.
Part of a trend
The case is a first in at least 15 years for the northwest Wyoming county, but doesn’t come as a surprise to experts like Riddell.
“It was really more of a question of ‘when’ than ‘if,’” he said, pointing to last year’s sudden rise in cases.
Fifteen cases were reported in the state last year, with none in Teton County. Before the 2025 outbreak, the state had not detected any cases in 15 years. The state’s first case this year was detected in an adult in Fremont County in May. Last year, the U.S. saw a 30-year high of the disease with a hotspot in the nearby state of Utah.
An ‘optimistic’ outlook
Measles has an extremely effective vaccination. Two doses of measles vaccine are 97% effective at preventing measles, according to the U.S. Centers for Disease Control and Prevention (CDC).
A community can achieve protection for most people through herd immunity if more than 95% of the population is vaccinated. Given Teton County’s relatively high vaccination rates, Riddell said he was “optimistic” that further community spread would be low. Still, he encouraged people to check their vaccine status, update it if needed and keep an eye out for symptoms.
People can check their vaccination status with their doctor or via the immunization registry in the state they were vaccinated in.
Vaccination coverage among Wyoming kindergartners is estimated at 93.6% for 2024-2025 school year, according to the CDC. That number across the U.S. decreased from 95.2% during the 2019–2020 school year to 92.5% in the 2024–2025 school year.
This article has been updated to include comments from Dr. Travis Riddell. — Ed.
