Minnesota has had two measles cases in 2014 making it one of 18 states included in the largest measles outbreak in 20 years.

So far, 288 people in the United States have contracted measles during the first five months of the year.

Nearly all of the cases have been associated with international travel by unvaccinated people, according to the Centers for Disease Control and Prevention.

They include the two in Minnesota, said Kris Ehresmann, director of Infectious Disease Epidemiology at the Minnesota Department of Health.

Travelers of all ages should make sure they have been vaccinated for measles, mumps and rubella, Ehresmann said.

One of Minnesota's cases was in an adult traveling for business who was unsure of his vaccination status. The other case occurred in a 19-month-old child who had visited India. The child had only received one dose of the MMR vaccine. Two doses are recommended.

"Anybody who's doing international travel, make sure you've had at least one dose of MMR if you're an adult," Ehresmann said. "If it's your kids make sure you're checking with your provider to see what's appropriate for them based on their age."