Minnesota's measles outbreak has expanded into Le Sueur County with two new cases in unvaccinated children, a development that was expected by health officials as they tracked the virus' transmission around the state.

Two other cases were reported Monday in the metro area, bringing the current outbreak's total to 58.

The Le Sueur County cases are linked to four cases in Crow Wing County through an extended family gathering that occurred somewhere in the state, and so it was not a surprise, according to health officials.

The first Crow Wing County case was announced two weeks ago and is linked to the ongoing outbreak in the metro area because that child had visited places in Hennepin County, which has been the center of the outbreak. On Friday, state health officials announced that three siblings of the initial Crow Wing County case had also become ill.

The Le Sueur County cases involve children under the age of 5. They have not been hospitalized and are recovering at home, according to information released by county officials Monday. Public health officials there have asked schools to contact parents of unvaccinated children and encourage them to get measles shots.

"The big message is to vaccinate, just can't say that enough," said Cindy Shaughnessy, public health director, who said other efforts are underway to spread the word.

Under the state's guidelines, children and adults in affected counties are urged to get the MMR shot, which protects against measles, mumps and rubella. If they have received one of the two recommended shots, they are urged to get the second shot as soon as possible to have the most protection. Ordinarily, the first shot is recommended at age 1 and the second around age 5.

"If it has been 28 days since that first one they should get their second one," Shaughnessy said.

In Crow Wing County, a local health provider has held a special MMR vaccination event that drew about 60 people who got the first or second dose, according to county administrator Tim Houle.

"We are not expecting a widespread outbreak, but for those who are not vaccinated they are at more risk," Houle said.

Measles is highly contagious and spreads easily when introduced to unvaccinated groups. Sneezing and coughing transmit the virus, but someone without immunity protection can catch the virus simply by breathing the air or touching surfaces that had come into contact with an infected person.

Parents, teachers and relatives may not immediately suspect that a child is infected with measles because the first symptoms resemble those of a cold. Typically, symptoms such as fever, coughing, watery eyes and runny nose persist for four days, and then a rash develops. Those infected can pass it on to others when symptoms begin and up to four days after the rash develops.

The other two cases announced Monday also include unvaccinated children, with one case in Hennepin County, bringing its total to 49 cases, and the other in Ramsey County, which now has had three cases.

This is the largest outbreak to hit Minnesota since 1990, when 460 were sickened.

At least 15 children have required hospitalization due to the seriousness of their illness.