The unvaccinated are behind a threefold spike in measles cases this year, the U.S. Centers for Disease Control and Prevention has found.

Of the 220 cases reported in 2011 so far, 87 percent did not get the vaccine, and 13 percent were too young to get the vaccine. No deaths have been reported. Most of the reported cases were people who traveled to Western Europe, Africa, or Asia. In the first half of 2011 alone, Europe had 26,000 cases of measles, including nine deaths, according to the World Health Organization.

Before the vaccine became available in the 1960s, an estimated 3 to 4 million people contracted measles each year in the U.S. Of those, about 500 died, some 48,000 were hospitalized, and 1,000 become permanently disabled due to brain inflammation.

Some adults don't realize they haven't had the shots, while most unvaccinated teens/children aren't given the shots because of their parents' religious beliefs or opposition to vaccines, according to the CDC.

The 8 percent of the U.S. population that is not immunized against measles are putting themselves and others at risk, says Patsy Stinchfield, Director of the Infection Disease Department at Children's Hospital and Clinics of Minnesota.

"Measles is one of the leading causes of death among young children,"
Stinchfield says, adding that it can be mistaken for a bad case of the flu.
Children can suffer for years before they die from the disease, she says, and there is an increased risk of brain inflammation and neurological problems if a child gets measles.

Getting the MMR (measles- mumps-rubella) vaccine is far safer than declining or delaying it, Stinchfield adds.

Measles symptoms include a fever, runny nose, bloodshot eyes, tiny white spots inside the mouth, and a rash that starts on the face and neck and spreads to the rest of the body.

Two doses of the vaccine provide lifelong immunity in 98 to 99 percent of cases, according to the CDC. The agency recommends a first dose at the age of 12 months and a second dose between the ages of 4 and 6.