Mumps is a contagious illness caused by a virus that infects the
salivary (parotid) glands, which are located between the ear and the jaw, and
that sometimes infects other glands, particularly the testicles (orchitis). The
glands become swollen and tender as a result of the virus.
Mumps can affect people of all ages, but it most commonly affects
children between the ages of 5 and 19. Mumps is rare in babies younger than a
year old, because they still have some protection against the virus from their
mothers. It is a mild illness in children younger than 2.
Mumps is uncommon in adults because most adults have either had the
illness as children or have been immunized with the measles, mumps, and rubella
(MMR) vaccine. When adults do get the illness, symptoms may be more severe, and
complications are more likely.
