Measles cases in the United States have reached a record high since the disease was declared eliminated from the country 25 years ago. Officials had declared measles eliminated in 2000, when there had not been continuous transmission for more than a year.

More than 1,200 measles cases have been confirmed in the U.S. so far this year. Most cases are in Texas, which accounts for about 2 out of 3 reported infections, according to an NBC News tally of state health departments.