Mumps is a contagious respiratory infection caused by the mumps virus, which infects the upper respiratory tract. People infected with mumps usually develop a characteristic swelling of the jaw and puffy cheeks, which is a result of swollen salivary glands (parotitis). The swelling can occur on one or both sides of the face. The mumps virus is a large enveloped virus that is part of the paramyxovirus family.
The infection is primarily spread through saliva or mucus from an infected person’s mouth, nose, or throat. The virus replicates in the upper respiratory tract and lymph nodes and is spread through direct contact with respiratory secretions or saliva or indirectly through contact with contaminated surfaces.
Infections with mumps used to be quite common, but due to the availability of a vaccine starting in 1967, in developed countries the number of cases has dropped significantly. In the US, there are usually less than 500 cases per year, but in some years there are a few thousand cases. The MMR (Measles, Mumps, and Rubella) vaccination is typically given to children in 2 doses prior to age six and is 88% effective in preventing infection.
Mumps outbreaks can happen at any time of the year, but often occur in the winter and spring. Close personal contact increases the risk of an infected person transmitting the virus to a non-immunized person. Mumps is not known to infect animals nor to be transmitted via animals.