Once eliminated from the United States — measles is back at record numbers with sustained spread across parts of the nation. With an unmistakable painful rash, the potentially life-threatening infectious disease is extremely contagious, especially in those that are not immunized. Look through the carousel to learn where and why the number of outbreaks is increasing. To learn your risk of getting measles based on where you live, visit ABCNews.com/measles and enter your ZIP code. | ABC News