Mumps is a viral illness that mainly attacks the salivary glands. Most often the parotid glands (in the cheeks) are infected, leading to the classic swollen-cheek appearance; other salivary glands may be infected as well. Besides the gland swelling, people with mumps may also have low-grade fevers, mild headaches, loss of appetite, and abdominal pain. The symptoms usually go away within 10 days or so. The virus is spread by coughing and sneezing, but can also be spread by an infected person touching something (like a toy) without washing their hands first to someone else who touches the toy and then touches her eyes, nose, or mouth. You can see symptoms from less than 2 weeks after exposure to as much as 3-1/2 weeks, and the virus can be found in a patient's saliva for up to a week before symptoms and over a week after the symptoms subside.
Roughly one out of three boys and men who have mumps after puberty develop orchitis swelling of the testes) on one side and rarely on both along with high fever and considerable pain. Adult women and girls who have reached puberty can develop mastitis (painful swelling of the breasts) or painful swelling of the ovaries. These symptoms usually go away in 1-2 weeks. Sterility is very rare after mumps even if both testes are involved. It is also possible to have pancreatitis (inflammation of the pancreas gland) with a mumps infection.
It is possible to develop a mumps-virus meningitis. This is not nearly as serious a problem as bacterial meningitis, which is fortunate because there is little we can do to treat it. Usually patients with mumps meningitis recover without permanent damage. It is also possible for a pregnant woman to have a miscarriage, especially early in pregnancy. Both meningitis and miscarriages after mumps are extremely rare.
We give mumps vaccine as part of the measles-mumps-rubella (MMR) vaccine. Usually a child receives two doses: one at 15 months, and one just before kindergarten or at age 11-12 years depending on state rules. There is now a combination vaccine which contains both MMR and the vaccine for chickenpox; this vaccine, called "MMRV", is given at the same time as the MMR vaccine has been given, and provides the same protection against all four diseases while cutting the number of needle pokes a child needs. For (the few) children who are already immune to measles and German measles a single mumps vaccine is also available. It takes 2 to 4 weeks after receiving the vaccine before you are fully protected, and getting the vaccine after you are exposed does not seem to keep you from getting mumps.