Mumps (infectious parotitis; epidemic parotitis) is a common, acute, viral infectious disease, principally of children, with worldwide distribution. It is frequently clinically characterized by fever and painful enlargement of one or more salivary glands. Inapparent infection is common and occurs in about onethird of infections. Sometimes postpubertal males with mumps may develop painful swelling of the testicles, usually only on one side, with sterility an extremely rare complication. Mumps is a vaccinepreventable disease, but the vaccine is not yet widely used on a global basis.

Etiology and Epidemiology

Mumps is caused by the mumps virus, a member of the genus Paramyxovirus of the family Paramyxoviridae. Mumps virus has an irregular spherical shape averaging about 200 nanometers in diameter and contains a single-stranded RNA genome.

Mumps is a contagious disease, only slightly less contagious than rubella and measles, transmitted from infected persons to susceptible individuals by droplet spread and by direct contact with saliva. Mumps virus has also been shown to be transmitted across the placenta to the fetus. There is no natural reservoir for mumps other than human beings, which means that a continuous chain of susceptible contacts is necessary to sustain transmission. Although the period of communicability may be from 6 days before salivary gland symptoms to 9 days afterwards, the period of greatest infectivity is about 48 hours before salivary gland involvement. There is no carrier state. Mumps has an incubation period from time of exposure to onset of salivary gland swelling of about 18 days with a range of 2 to 3 weeks.