Vials of the measles mumps and rubella (MMR) vaccine are displayed in February in Lubbock, Texas. (AP Photo/Julio Cortez, file)

Fourteen people in northeast Wisconsin have been infected with measles, state health officials said Friday.

The Department of Health Services first reported nine cases of measles in Oconto County in early August. All five of the newly reported cases are linked to that outbreak.

Officials said ages of the infected range from 7 months to 53 years old. Most are unvaccinated.

Stephanie Schauer, the state’s immunization program director, said one dose of measles vaccine is 93% effective at preventing infection, and the recommended two-dose course is 97% effective. In the absence of vaccines, she said, measles is “one of the most highly infectious diseases that we have.”

“If someone is in an indoor space with measles and leaves, the virus remains suspended in the air for up to two hours,” Schauer said — meaning it can infect someone who comes into contact with the virus even without face-to-face contact with an infected person.

No hospitalizations or deaths have been linked so far to the outbreak in northeast Wisconsin, officials said.

Schauer said nationally, about 92% of new measles cases are in those who are unvaccinated.

The confirmation of new spread of the disease comes days after state health officials announced possible measles exposures at two Wisconsin truck stops. In that case, an out-of-state traveler who was infected with measles was at the Flying J Travel Center on 70th Avenue in the St. Croix village of Roberts on Aug. 4 between 7:15 and 10 a.m., and at the Pilot Travel Center on Milwaukee Road in Beloit on the same day between 11:45 a.m. and 2:30 p.m.

Measles is a potentially deadly respiratory illness, especially for the very young or old and those with weakened immune systems. Symptoms typically appear 10 to 21 days after exposure. They include a runny nose, high fever, tiredness, cough, red and watery eyes, a red rash and raised bumps that start at the hairline and move to the arms and legs.

People can check their own immunization records with the state or their provider. Wisconsin also offers programs to help uninsured children and adults receive vaccines at no cost.

Wisconsin has one of the lowest measles vaccination rates among children in the country. As of 2023, 81% of 2-year-olds had the vaccine, down from 88% in 2013. Some Wisconsin counties had vaccination rates closer to 50%.