Montgomery County health officials said they have confirmed two cases of measles and are looking for others who may have been exposed to the highly contagious virus.

These are the first cases since 2009, though state health officials warned last week about a passenger who rode an Amtrak train who may have been exposed to the virus. A non-Maryland resident who traveled to the state also was diagnosed in June with measles.

The two children arrived in the country Aug. 24 and were unvaccinated. They had not yet shown symptoms on Aug. 29 when they went to the Suburban Washington Resettlement Center at 8700 Georgia Ave. in Silver Spring and possibly exposed others.

Those who have had measles or have gotten two doses of the measles-mumps-rubella vaccine are not at risk, nor are those born in this country before 1957. But parents of nfants, unvaccinated pregnant women and those with weakened immune systems who may have been exposed should call their health care providers. A preventive medicine may be needed.

Measles is spread through coughing and sneezing or contact with nose or throat secreations. Symptoms appear in two stages – a fever, runny nose and watery eyes and cough and then a rash on the third to seventh day.

It’s been virtually eliminated in this country because of the vaccine, but cases arise when people travel oversees or unvaccinated people come to the United States. School kids and citizen applicants are required to be vaccinated.

For more information on measles, go to http://www.cdc.gov/measles.