Mortality is rare and usually occurs in patients older than 19 years. Fatal mumps nephritis and myocarditis has been reported. Isolated mumps cerebellitis has been reported. Mumps orchitis is common in postpubertal males, but it rarely causes sterility unless there is bilateral involvement. It should be considered in any patient presenting with scrotal swelling.
Mumps is one of the most frequent causes of unilateral hearing loss.
Many infections are subclinical. Headache is common. Systemic symptoms may be lacking, especially in children. Others may present with one of the many complications of the infection without the parotid swelling. The testicles are edematous and acutely painful.