Pennsylvania has surpassed 1,000 measles cases this year, state health officials said Monday, making it the largest state outbreak in more than three decades. The U.S. is enduring its worst year for measles since 1991, with nearly 3,900 reported cases, according to the CDC. The nation has seen eight reported measles-associated deaths in the past two years " more than the combined total of reported deaths over the previous three decades. Since the beginning of last year, large outbreaks have been reported in several states, including Texas and Utah, as well as South Carolina, which had the largest with 997 cases reported.