A measles investigation amid a large, ongoing outbreak at the Arizona-Utah border has hit a roadblock as the first probable case identified in the Salt Lake City area refuses to work with health officials, the local health department reported this week.

There have been over 150 cases collectively across the two states, mostly in northwestern Mohave County, Arizona, and the southwest health district of Utah, in the past two months. Both areas have abysmally low vaccination rates: In Mohave County, only 78.4 percent of kindergartners in the 2024–2025 school year were vaccinated against measles, according to state records. In the southwest district of Utah, only 80.7 percent of kindergartners in the 2024–2025 school year had records of measles vaccination. Public health experts say vaccination coverage of 95 percent is necessary to keep the disease from spreading in a community.

While the outbreak has largely exploded along the border, cases are also creeping to the north, toward Salt Lake County, which encompasses the city. Utah County, which sits just south of Salt Lake County, has identified eight cases, including a new case reported today.

Uncooperative case

Salt Lake County likely has a new one, too—the first for the county this year—as well as possible exposures. But, they can’t confirm it.

County health officials said that a health care provider in the area contacted them late on Monday to tell them about a patient who very likely has measles. The officials then spent a day reaching out to the person, who refused to answer questions or cooperate in any way. That included refusing to share location information so that other people could be notified that they were potentially exposed to one of the most infectious viruses known.

“The patient has declined to be tested, or to fully participate in our disease investigation, so we will not be able to technically confirm the illness or properly do contact tracing to warn anyone with whom the patient may have had contact,” Dorothy Adams, executive director of Salt Lake County Health Department, said in a statement. “But based on the specific symptoms reported by the healthcare provider and the limited conversation our investigators have had with the patient, this is very likely a case of measles in someone living in Salt Lake County.”