Nassau health officials are issuing a warning on the threat of measles.

The CDC says that measles have been diagnosed in 21 states including New York so far this year.

"Measles was thought to be eradicated in the United States. However there are many people in the United States who chose not to be vaccinated," says Dr. Paul Pipia, NUMC medical director. "So when you choose not to be vaccinated, you are now susceptible to get the measles. If you have been vaccinated you won't get the measles."

Some of the symptoms include high fever, red spots and both a flat and bumpy rash.

If you have symptoms, doctors say don't just go to a hospital. They say to first call the emergency room so they can take precautions before treating you.