The Arkansas Department of Health says nearly 500 cases of mumps have been reported in northwest Arkansas, and the number is continuing to grow.
The department says 492 people have confirmed or suspected cases of the virus.
State Epidemiologist Dr. Dirk Haselow says the disease is being spread among children at schools, and the state is "very concerned" by the growing number of new cases. The state says cases have been reported in the Springdale, Rogers, Bentonville and Huntsville school districts.
The ADH will be offering a free vaccination clinic for Mumps, Measles and Rubella Thursday from 11 a.m. to 7 p.m. in the Jones Center in Springdale. The vaccine will be to patients at no cost, but they encourage those with insurance to bring their cards.
The outbreak was first reported August 31 and the health department expects cases to keep multiplying over the next several months.
The Oklahoma Department of Health said they are currently investigating 70 cases of mumps - 68 in Garfield County and two in Kay County. The median age of those affected is 14.5. None have required hospitalization.
Mumps is a viral infection that causes swelling in the salivary glands and cheeks. Those with the illness may also have headaches, fatigue, muscle aches and low-grade fevers.
The Associated Press contributed to this report.