An Idaho man has contracted measles, and health officials are working to contact anyone who may have been exposed to the highly contagious disease.

The man was unvaccinated, the Idaho Department of Health and Welfare said in a news release Wednesday afternoon, and he was exposed during international travel. He was hospitalized for a time but is now recovering at home.

“Measles is very rare in Idaho and in the United States now, largely due to mass vaccination,” said Dr. Christine Hahn, the medical director of the Idaho Division of Public Health. Just three cases have been reported in the state in the past two decades.

“It’s not something we see very commonly, but when we do see it we worry about spread in pockets of people who are not vaccinated. For those of us who are vaccinated, we don’t have to worry about it,” she said.

People with measles become infectious about four days before symptoms begin, Hahn said. During his infectious period, the Idaho man spent time at the Boise airport on Sept. 13 and in the Nampa area on Sept. 14 and 15. The measles virus can live in the air for up to two hours after an infected person leaves the area, and it is so contagious that up to 90% of people who are not immune will become infected.

Public health workers with local health districts are working to find people who may have been exposed to the man, the Department of Health and Welfare said. Measles symptoms include fever, runny nose, cough and rash. Public health officials say people who have been exposed should call a health care provider and watch for symptoms for 21 days.

“There are no known additional cases at this point — we just found out about this case yesterday,” Hahn said. It could take another week or so before health officials can determine if there are any other cases, she said.

The measles vaccine is typically given in two doses in early childhood, as part of a combination vaccine that also protects against mumps and rubella.

The U.S. Centers for Disease Control and Prevention estimates that just under 84% of Idaho kindergartners were fully vaccinated against measles, mumps and rubella during the 2021-2022 school year, the most recent available. That compares to an estimate about 93% nationwide.

Measles is an airborne disease and typically causes a cough, red eyes and a facial rash. Serious complications are mostly seen in children under five and adults over 30 and include blindness, encephalitis and pneumonia.