Mumps is an illness caused by a virus.
It affects glands that produce saliva which are located near the jaw. It can occur on one or both sides of the jaw area of the face and neck. Even if an infected person does not have swelling, they can still pass the virus on. The mumps virus is spread by contact with an infected person's saliva or droplets that might be released through the nose or mouth when the person coughs or sneezes.