Infection with a myxovirus and predominantly a disease of childhood and early adult life. It is highly infectious from person to person for two or three days before the swelling of the glands appears, with epidemics usually occurring in the winter and spring. Immunisation with MMR vaccine gives a high degree of protection against the disease, the incidence of which is falling sharply (see MMR VACCINE; IMMUNISATION).

There is an incubation period of 2–3 weeks after infection before the glands begin to swell. The parotid gland, situated in front of and below the ear, is generally the first affected. The swelling usually spreads to the submaxillary and sublingual glands lying beneath the jaw. The patient is feverish and the affected gland is tender. In 15–30 per cent of males, inflammation of the testicles (orchitis) and may result in partial ATROPHY of the testicles, but practically never in INFERTILITY. In a much smaller proportion of females with mumps, inflammation of the OVARIES or BREASTS may occur. Inflammation of the PANCREAS, accompanied by tenderness in the upper part of the abdomen and digestive disturbances, sometimes results, and MENINGITIS is also an occasional complication which may lead to hearing loss. The various complications are found much more often when the disease affects adults than when it occurs in childhood.

There is no specific treatment but ANALGESICS and plenty of fluid should be available. The child may need to be in bed for a few days and should not return to school until the symptoms have settled. Adults with orchitis may need strong painkillers, and CORTICOSTEROIDS may be required to reduce the painful swelling.