This virus is spread by direct contact via the respiratory route.
Infection occurs throughout childhood.
During adulthood, infection is likely to produce more severe disease, including orchitis . Although mumps virus can cross the placenta, no evidence exists that mumps infection in pregnancy causes congenital malformations. The incidence has declined markedly since the introduction of the mumps vaccine. Outbreaks can occur in highly vaccinated populations, indicating that mumps transmission can be sustained among the few persons not protected by vaccination. Recent studies suggest that the HN glycoprotein contributes to cytopathology of an infection via the neuraminidase activity.