Mumps

Mumps is an acute disease of children and young adults, caused by a paramyxovirus of which there is only a single serotype. Humans are the only known host for mumps virus, which is spread via direct contact or by airborne droplets from the upper respiratory tract of infected individuals. Mumps if frequently reported in children aged 5-9 years of age, although both adolescents and adults may be affected. After an incubation period of some 2 to 4 weeks mumps begins with non-specific symptoms such as myalgia, headache, malaise and low-grade fever. Within days, these symptoms are followed by unilateral or bilateral swelling of the parotid salivary glands, with other salivary glands affected in 10% of cases.

Normally mumps is a mild, self-limiting disease and disappears without sequelae. However, complications may occur such as encephalitis or sensorineural deafness. Orchitis (a painful inflammation of the testes) occurs in 20% of young adult males who develop mumps.

Mumps vaccines

Live attenuated mumps vaccines based on live attenuated virus strains including the Jeryl-Lynn, RIT 4385, Leningrad-3, Leningrad-Zagreb, Urabe Am9, S79, Rubini, and others, have been available since the 1960s. However, due to the low level of seroconversion obtained with the Rubini strain, WHO has recommended that this strain should not be used in national immunization programmes. These vaccines are produced by growing the virus in cell cultures or in embryonated chicken eggs. The virus is then purified, formulated with a stabilizer such as gelatine or sorbitol and lyophilized. Mumps vaccines are available as a monovalent vaccine, a bivalent measles-mumps vaccine, or as a trivalent measles-mumps-rubella vaccine (MMR).

Mumps vaccine standardization

Written Standards

Requirements for Mumps Vaccine (Live) were adopted by the WHO Expert Committee on Biological Standardization in 1986. As mumps vaccines are routinely used in multi-antigen combinations with measles and rubella vaccines, WHO updated the guidance for the three vaccines in 1992 into a single document which contains the requirements for the three monovalent vaccines and MMR. A note was added concerning the inclusion of serum in the production medium for the mumps component in 1993.