In some communities, anti-immunisation activists have spread false claims about the measles, mumps and rubella vaccine, causing concern among parents about innoculating their children.
When many people in a community have not been vaccinated, the disease can spread quickly. It is one of the most contagious diseases in the world and can cause serious complications, especially among young children, adults with weakened immune systems and the elderly.
The states that have reported cases to CDC this year are: Arizona, California, Colorado, Connecticut, Florida, Georgia, Illinois, Indiana, Iowa, Kentucky, Maryland, Massachusetts, Michigan, Missouri, Nevada, New Hampshire, New Jersey, New York, Oregon, Texas, Tennessee and Washington.