Mumps is caused by a paramyxovirus. The infection is seen worldwide and affects both sexes equally. Mumps remains endemic throughout most of the world. Epidemics occur during all seasons, but are more frequent in late winter and spring. Its occurrence appears to be primarily related to lack of immunization rather than waning of immunity.
Humans are the only known natural host of the mumps virus.
Lifelong immunity usually follows clinical or subclinical infection, although second infections have been reported. Parotitis may be unilateral or bilateral, usually occurs within the first two days and may first be manifested by earache and tenderness on palpation of the angle of the jaw. The swelling slowly subsides within 3-7 days, but can last longer. Some children could have an erythematous rash, most prominent on the trunk. The mumps virus is spread by direct contact via the respiratory route, by coughing, sneezing, or simply talking with a person infected.