Mumps is a contagious viral infection caused by the mumps virus, which primarily affects the salivary glands, particularly the parotid glands located near the ears. The infection causes these glands to swell, resulting in the characteristic puffy cheeks and tender, swollen jaw. Symptoms usually appear 16-18 days after exposure to the virus and can include fever, headache, muscle aches, fatigue, and loss of appetite, followed by the swelling of the salivary glands.

Mumps spreads through respiratory droplets when an infected person coughs or sneezes, as well as through direct contact with saliva or contaminated surfaces. It is most contagious a few days before and after the onset of symptoms.

While mumps is generally a mild disease in children, it can lead to serious complications, especially in adults. Complications can include inflammation of the testicles (orchitis) in males, which can lead to infertility, inflammation of the ovaries (oophoritis) or breasts (mastitis) in females, meningitis (inflammation of the lining of the brain and spinal cord), and pancreatitis. Deafness, though rare, can also occur.

Vaccination with the measles, mumps, and rubella (MMR) vaccine is the best way to prevent mumps. The vaccine is usually given in two doses during childhood, which provides long-lasting immunity. High vaccination coverage is essential to maintain herd immunity and prevent outbreaks.