Seven Midwestern states are dealing with a mumps epidemic, the nation's first major outbreak of the disease in 20 years. And health officials expect the number of cases to climb even higher in coming weeks. Many more cases than normal are being reported in Nebraska, Kansas, Illinois, Missouri, Wisconsin and Minnesota with Iowa the hardest hit state so far.

Mumps was once a common childhood illness but it had been virtually eradicated with widespread use of the measles, mumps and rubella (MMR) vaccine first introduced into the U.S. in 1967.

The number of cases declined further after routine vaccination was recommended for children in 1977 and after a second dose of the MMR vaccine was implemented in the 1990s.

What's the mumps? Mumps is a contagious disease caused by a virus. Common symptoms include fever, headache, and a swelling of the glands around the jaw. Symptoms are not usually severe in children. In teenagers and adults, the symptoms can be more severe and complications are more common but still rare.

How does it spread? The disease is spread the same way as colds -- coughing and sneezing and touching contaminated surfaces. Symptoms can show up 12 to 25 days after infection and people are contagious from three days before getting symptoms until nine days after symptoms start. Health officials think the current outbreak may be traced to two passengers on commercial flights to and from Iowa.

What can you do to protect yourself? Mumps season lasts from late winter to spring. Practice good hygiene -- wash your hands regularly, cover your mouth when you cough. Avoid sharing drinking cups and eating utensils. Avoid close contact with sick individuals. Get vaccinated. And if you do get sick, stay home from school.

What if you do get sick? Unfortunately, there is no specific treatment for mumps other than relieving the symptoms. The disease usually runs its course in about five days. On the bright side, if you've had the mumps, you're probably immune. Before U.S. children began receiving routine mumps vaccinations in 1967, almost everybody got the mumps and thus gained immunity from future infections.