LITTLE ROCK — The Arkansas Department of Health said Wednesday it is investigating an outbreak of mumps in Springdale.

Two cases of the viral illness have been confirmed and several suspected cases have been identified, the agency said in a news release. The cluster of cases is the largest in Arkansas since 2010.

The Health Department is requiring Springdale School District students with exemptions from the mumps, measles and rubella, or MMR, vaccine to be excluded from school for 26 days from the date of exposure and until the outbreak has ended. Students with nonmedical exemptions who receive the recommend doses of MMR vaccine may return to school immediately, the agency said.

Mumps is transmitted by direct contact with respiratory droplets or saliva from an infected person. It is best known for painful, swollen salivary glands that show up as puffy cheeks and swollen jaw. Boys may also have painful, swollen testicles.

Other symptoms include fever, headache, muscles aches, tiredness and loss of appetite. There is no treatment, and symptoms usually resolve themselves within a few weeks. Mumps is usually a mild disease in children, but adults may have more serious symptoms with complications.