First measles case reported in Teton County
JACKSON (WNE) — An unvaccinated adult living and working in Grand Teton National Park recently contracted measles, becoming the first person in Teton County to test positive for the highly contagious virus in recent memory.
“Measles is here,” Dr. Travis Riddell said Monday. “For a long time, we’ve thought this was more a question of ‘when,’ than ‘if,’ and have been preparing accordingly.”
The person was not admitted to St. John’s Health following a visit last Thursday and is now recovering in isolation. Their symptoms date back to June 17, Riddell said.
State officials learned about the case Saturday, after the person tested positive, kicking off an investigation to track down other people who may have been exposed to the virus. The person likely contracted measles in Wyoming, investigators found, though they haven’t pinned down a specific source.
“The fact that it was likely acquired in Wyoming indicates that there’s a potential that there was an unrecognized case, or unrecognized transmission prior to this,” said Dr. Alexia Harrist, state health officer at the Wyoming Department of Health.
Officials aren’t aware of any other cases beyond the one person, Riddell said. Other measles cases could, however, pop up in people exposed before the person was diagnosed.
The person likely contracted the virus in the park, Riddell said. He concluded as much because the person appears to have stayed in Grand Teton National Park during their incubation period, the period between when they were infected and when they started showing symptoms.
It can take up to 21 days for people exposed to the measles virus to develop symptoms.
People who have received the measles, mumps and rubella vaccine are unlikely to get sick if exposed to the virus, officials said. Unvaccinated individuals, babies less than a year old who are too young to receive vaccines, and immunocompromised people are at higher risk.
This story was published on June 30, 2026.
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