Why It Matters
Wyoming’s health authorities declared a measles outbreak in Teton County on Monday after confirming three cases of the highly contagious virus in the region during peak summer tourism season. The outbreak marks a significant public health concern for a state that had gone 15 years without reporting measles cases before last year, and it comes as millions of visitors flock to Jackson and Grand Teton National Park annually.
What Happened
The Wyoming Department of Health announced the measles outbreak following confirmation of three cases in Teton County this summer. The first case was reported on June 28, with exposures documented at Colter Bay Village restaurants on June 17-18, a Colter Bay convenience store on June 20, and a Target location in Jackson on June 25.
A second case was confirmed over the weekend, followed by a third case confirmed Monday. Health officials indicated that exposures associated with the two most recent cases occurred between July 4-7 at unspecified locations in the county.
State health officials have instructed anyone who may have been exposed to monitor themselves for three weeks and to contact their doctor before seeking in-person care if symptoms develop. According to Monique McBride, Wyoming Department of Health Chief Policy and Communications Officer, the outbreak is defined as a “chain of transmission involving three or more confirmed or probable cases that are epidemiologically linked.”
By the Numbers
Measles had been eliminated in the United States in 2000, but Wyoming reported no cases for 15 years until July 2025, when the state confirmed its first case in Natrona County. By the end of 2025, Wyoming had documented 13 additional measles cases statewide. Early 2026 brought another confirmed case in Fremont County before this week’s Teton County outbreak.
National trends show a sharp increase in measles activity. The U.S. recorded just 13 measles cases in 2020, but that number surged to 2,289 cases in 2025, resulting in 3 deaths. As of mid-2026, more than 2,231 measles cases had been confirmed nationally with no reported deaths.
Vaccination rates in Wyoming present a potential vulnerability. In 2025, 93.6 percent of kindergarten students were vaccinated against measles, mumps, and rubella—a decline from the 97 percent vaccination rate recorded in 2012-13.
Context and Concerns
Measles is highly contagious and can spread rapidly through populations with lower vaccination coverage. The virus poses particular risk to unvaccinated individuals, young children, and those with compromised immune systems. Health officials note that one to three deaths occur per 1,000 children infected with measles who develop complications from the disease.
The timing of this outbreak during Teton County’s peak tourist season raises concerns about potential further transmission. Millions of people visit Jackson and Grand Teton National Park each summer, creating conditions for rapid disease spread if vaccination rates remain suboptimal.
What’s Next
Wyoming health officials will continue investigating the chain of transmission and identifying additional potential exposures. The state is expected to urge residents and visitors to verify their measles immunity status and to consider vaccination if not previously inoculated.
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