The Minnesota Department of Health says at least 28 of the outbreak’s victims are Somali-American. Just one is known to have received the MMR vaccine, which protects against measles, mumps and rubella.

Somali-Americans in Minnesota once had higher vaccination rates than the general population. But that changed following news reports in 2008 about high rates of autism among Somali-American students in Minneapolis Public Schools.

Kris Ehresmann, infectious disease division director at the Health Department, said anti-vaccine activists seized on the 2008 news “almost immediately,” spreading fears about a debunked link between the MMR vaccine and autism.

Those fears have stuck. As of 2014, just 42 percent of Somali-Minnesotan 2-year-olds had received the MMR vaccine, compared with 89 percent of all other 2-year-olds.

“Basically, they’re a tinderbox for an outbreak,” Ehresmann said.

This year’s outbreak, the state’s first since 2011, began about March 30 and spread through a Hennepin County day care. Hennepin County has seen 30 cases overall and Stearns and Ramsey counties one each. All of the victims are under age 6.

Measles can be fatal, but some find the specter of autism even scarier.

A supposed link between the MMR vaccine and autism, first published in the Lancet medical journal in 1998, was based on falsified data from the study’s author, the British surgeon Andrew Wakefield. The British journal later retracted the study, and dozens of studies since have found no link between the MMR and autism.

Nonetheless, the myth persists, largely because autism’s true cause remains unknown and because vaccine skeptics remain vocal. Wakefield himself, who has lost his license to practice medicine, has met with Somali-Minnesotans to stoke fears of the MMR vaccine.

The Health Department was meeting with Somali-Minnesotans on Friday about the importance of vaccinations. Vaccine skeptics have their own meeting scheduled for Sunday, Ehresmann said.

“The problem is that the anti-vaccine groups are quite aggressive,” she said. “We need to scale things up much more than we have.”

The measles was declared eliminated in the United States in 2000, but Minnesota and other states see sporadic cases, typically linked to international travel. That was the case in 2011, when a Minnesota child contracted the disease on a visit to Kenya.

The latest outbreak has prompted St. Paul Public Schools to warn parents about the disease’s dangers and stress the importance of immunization.

School nurses are contacting the parents of unvaccinated children, the district translated letters regarding immunization, and health officials attended a Somali cultural event Friday evening to promote vaccination.

Last school year, 9 percent of the St. Paul district’s kindergartners had not received the MMR vaccine; statewide, that figure was 7 percent.

The MMR vaccine is given to children in two doses. The Health Department recommends that Somali-Minnesotan children statewide who have received their first dose of MMR vaccine — often done at 12 months — get their second dose now.

This special vaccine schedule is commonly recommended during outbreaks instead of waiting until 4 to 6 years old for the second dose.

Diane Madlon-Kay, a physician and University of Minnesota professor who works with many Somali-Americans, said it’s difficult to overcome anecdotes from parents who swear their child is autistic because of a vaccine.

“When you’ve got a parent who’s convinced that’s the cause and telling other parents in a tight-knit community, it’s just really hard to argue against that,” she said.

Madlon-Kay said the parents often authorize other vaccines for their children but refuse the MMR or say they’ll get it some other time.

“I’ll always say clearly there hasn’t been any proven association with autism and it’s very important that the child get this one,” she said. “They’ll smile and nod and say, ‘Yes, yes, I understand, but not today.'”