A mumps outbreak brought 427 cases of the virus to northwestern Arkansas, the state's department of health reported Friday. Thirteen workplaces and three school districts in Benton, Washington, and Madison counties reported sick students and employees, with the majority of cases occurring in school aged children. Two-hundred-eighty of the sick were aged five to 17.

The numbers were based off of those who displayed symptoms along with those who received positive lab confirmation of the virus. The Arkansas Department of Health battled against further cases by requiring students who have not had a mumps vaccine to stay home from school for 26 days or the duration of the outbreak, whichever is longer.

The mumps, a viral infection of the salivary glands, is spread from person to person through infected saliva or by breathing in saliva droplets. The most common symptoms are swollen salivary glands that cause a person's cheeks to swell. Headaches, fever, muscle aches, fatigue, and loss of appetite are also common.

Because it’s a virus, there are no effective antibiotics. Most people recover from the mumps within two weeks. Complications like encephalitis, or brain swelling, can occur if the virus spreads through the bloodstream to the brain. Though uncommon, it can be deadly.

Hearing loss and miscarriages can also occur, according to the Mayo Clinic. The virus hasn't been common in the United States since the advent of the measles, mumps, and rubella (MMR) vaccine in 1967. Before the vaccination was commonplace, 186,000 cases were reported each year, according to the Centers for Disease Control and Prevention. The U.S. saw a 99 percent drop in cases of the virus after the vaccine was implemented. 

In 2012, there were just 229 reported cases of the virus throughout the United States. This year has already seen at least 1,897 cases. That number is sure to increase once the final count comes in from Arkansas.