Mumps usually occurs in outbreaks, most often between the ages of 5–9, usually in the winter and spring in temperate climates but at any time in the tropics. After infecting the upper respiratory tract, this contagious virus spreads to the salivary glands, the lymph nodes, the blood, and throughout the body. Symptoms at first are non-specific, followed by painful swelling of the face from parotitis. Complications are rare. Deafness may occur, also inflammation of the testes, breasts, ovaries, pancreas, meninges, and brain. Testicular inflammation may result in reduced fertility and, rarely, sterility.

Symptoms and complications are more common in males and more severe in adults. About one third of infected persons have no symptoms. Humans are the only natural host of the virus. In places where mumps is common, the disease is usually diagnosed clinically. In cases of doubt, antibody testing, viral cultures, or real-time reverse transcription polymerase chain reaction may be needed. The virus is an RNA virus of the family Paramyxoviridae. It is transmitted by respiratory secretions, droplets, saliva, or by direct contact.

The disease has a long history.  It was mentioned in the Chinese medical literature as early as 640 BC. Hippocrates observed an outbreak on the island of Thasos around 410 BC and wrote about it in the first book of Epidemics in the Corpus Hippocraticum. He called the disease “parotitis” from the Greek words “para” (near) and “ous” (ear) describing the location of the painful parotid glands located near the ears. The Roman Galen and the Persian Rhazes also wrote about the disease.

The word “mumps” seems to have been first mentioned about AD 1600 as the plural of “mump”, meaning to grimace or whine. The disease was likely called mumps because of the facial expression caused by the painful swelling or difficulty in swallowing. The word “mumps” was also used to signify sullenness or displeasure.

Mumps is sometimes called “epidemic parotitis”. It was described in detail in 1790 by Robert Hamilton in the Transactions of the Royal Society of Edinburgh. In late 19th century, the physicians Auguste Témoin from France and Harald Iversen from Denmark described it independently and showed it was caused by a filterable agent, later identified as a virus. During the First World War, mumps caused much discomfort among soldiers. In 1934 Claude D. Johnson and Ernest William Goodpasture discovered the virus itself by  finding that rhesus macaques exposed to human saliva developed the disease. They showed that mumps could then be transferred to children by filtered and sterilized bacteria-free preparations of macerated monkey parotid tissue, showing that it was a viral disease. This paved the way for development of a vaccine.

In 1948, John Franklin Enders and his colleagues cultivated the mumps virus in chick embryos, leading Maurice Hilleman to develop the first mumps vaccine in 1963. It was later combined with vaccines for measles and rubella to create the highly effective MMR (measles, mumps, rubella) vaccine in 1971. Since then, mumps cases have significantly decreased in many parts of the world, but outbreaks still occur, particularly in communities with low vaccination rates or among individuals who have not received the recommended two doses of the MMR vaccine.