Mumps is caused by the Mumps Virus (it doesn’t have a name in Greek or Latin). It’s quite rare these days because of childhood vaccination with the MMR vaccine, but there have been outbreaks in college dormitories, military barracks, and summer camps. Fever begins 12 to 25 days after exposure (the “incubation period”).
The disease begins with a fever and non-specific symptoms like fatigue, body aches, headache. Then 2-3 days later, salivary glands swell. The most common one is the parotid gland on the jaw bone (one or both sides), no other disease causes this, so diagnosis is easy.
Most people recover within 2-3 weeks. The main complication is testicular pain and swelling, affecting up to a third of men, beginning 5 to 10 days after the fever. Women can have pain in an ovary. Other complications like brain or heart disturbances, or deafness, are quite rare. And mumps itself is quite rare too.