Measles outbreak tracked in Maryland

ROCKVILLE, Md., April 15 (UPI) -- Health officials in Maryland say four people have been diagnosed with measles in the state's first outbreak since 2001.

Three of the four cases are linked to a Montgomery County man who contracted measles outside the United States in February, The Washington Post reported Tuesday.

Health officials said most recent measles outbreaks occur in foreign-born residents who have never been immunized. Immigrants seeking citizenship and children starting school must show proof of measles vaccination, the newspaper said.