Measles can cause serious health complications, such as pneumonia or encephalitis, and even death. Children younger than 5 years of age and adults older than 20 years of age are at high risk of getting a serious case of measles.easles was eliminated from the U.S. in 2000 (elimination is defined as the interruption of continuous measles transmission lasting more than 12 months). Since elimination was declared in 2000, the annual number of people reported to have measles ranged from a low of 37 people in 2004 to a high of 668 people in 2014.