U.S. measles cases in 2013 may be most in 17 years

This year is on track to be the worst for measles in more than a decade, according to new numbers released Thursday by the U.S. Centers for Disease Control and Prevention. And people who refuse to vaccinate their children are behind the increasing number of outbreaks, health officials say.

There were 159 cases of measles in the United States from January 1 through August 24, according to the CDC. If that trend continues, there will be more cases in 2013 than in any year since 1996, when some 500 cases were reported. The number would also surpass that of 2011, when there were 222 cases.

Measles cases in the United States numbered in the hundreds of thousands before the advent of vaccination, and dropped dramatically throughout the 1960s. The disease was thought to have been eradicated in 2000, but the numbers have recently crept back up, largely because of visitors from countries where measles is common and because of vaccine objectors within the United States. Nearly two-thirds of the reported cases happened in three outbreaks in communities where many people don't vaccinate their children for religious or philosophical reasons.