Minnesota health officials reported seven new measles cases Thursday, bringing the case count to 41 in an outbreak that has now infected its first adult and has begun to spread beyond the state's Somali community.

It has also moved to a new part of the state. A child residing in Crow Wing County has become infected, one of three cases announced this week involving people who aren't from the Somali community.

Health investigators believe the child was exposed in Hennepin County, where the outbreak has been concentrated, but they are watching for new cases in Crow Wing as well as in other parts of the state where the child traveled.

"It is very possible that we could see cases appearing in different parts of the state where there are pockets of unvaccinated kids," said Kris Ehresmann, infectious disease director for the Minnesota Health Department.

Also Thursday, state officials said they are considering imposing mandatory isolation and quarantine orders on some people who have been exposed to the infection but are not heeding advice to avoid public places where they might infect others with the highly contagious disease.

"We have some people who have not followed what we asked, and they have been blatant in exposing other people," Ehresmann said. "They have potentially spread the disease in other locations."

All cases until now have been in individuals without immunity protection, but two of the new cases involved people who fell ill even though they had received both recommended doses of the MMR vaccine, the shot that protects against measles, mumps and rubella.

One is a health care worker — the first adult to be struck in this outbreak — exposed to several infected patients, Ehresmann said.

Although two doses of the MMR vaccine provide 97 percent protection against the measles, according to the U.S. Centers for Disease Control and Prevention, some who have been inoculated can still become infected, especially in an outbreak.

Even so, Ehresmann said, individuals who have been vaccinated "tend to have much milder" issues.

To help control the outbreak's spread, the Health Department broadened its call for the unvaccinated to get the MMR vaccine.

All children over age 1 and all adults born after 1956 should get vaccinations if they had not already had them, health officials said. They also said children living in affected counties, as well as all Somali-American children statewide, should get the second MMR shot if they had the first shot at least 28 days ago. Typically, the shots are given around age 1 and between 4 and 6 years. Accelerating the schedule will provide children with extra protection, health officials said — a step that is often taken during outbreaks.

In addition to Hennepin and Crow Wing Counties, there are two cases in Ramsey County. A Stearns County case that was announced last week has since been ruled out as measles.

Since the outbreak was first detected three weeks ago, health investigators have contacted about 2,500 people exposed to known cases at known locations, including child-care centers, health care settings and households.

People who were exposed and were not vaccinated are being asked to stay home from work, school, child care and other public gathering places for three weeks.

The public health control effort has involved 70 state workers at a cost of $207,000, the department said. Some county and private health care organizations have also participated in follow-up efforts.

Measles is no longer naturally occurring in the United States. State health officials believe the current outbreak was most likely caused by someone who caught measles in a foreign country.

This is the largest outbreak in Minnesota since 1990, when more than 450 people were infected. Measles symptoms include a high fever, cough, runny nose and watery eyes, followed by a rash that typically spreads from the head to the rest of the body. It can lead to pneumonia and swelling of the brain. Many of those infected in this outbreak have required hospitalization.

Glenn Howatt • 612-673-7192