Clinical Questions & Answers on Mumps
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- What causes mumps?
- What are the clinical manifestations of mumps?
- Are there other causes of parotitis?
- What is the incubation period and period of infectiousness?
- How is the mumps virus transmitted?
- What complications can be caused by mumps?
- What are the long-term effects of mumps?
- What is the case definition for mumps?
A: Mumps is a viral illness caused by a paramyxovirus of the genus Rubulavirus.
A: The classic symptoms of mumps include parotitis in about 50% either unilateral bilateral, which develops an average of 16 to 18 days after exposure. Swelling can also be seen in the submandibular and sublingual gland in a small percentage. Nonspecific symptoms including myalgia, anorexia, malaise, headache, and low-grade fever may precede parotitis by several days. As many as 40%–50% of mumps infections are associated with nonspecific or primarily respiratory symptoms, particularly among children less than 5 years of age. Only 30-40% of mumps infections produce typical acute parotitis. In 15-20% of infections, cases are asymptomatic.
A: Yes, but only mumps causes epidemic parotitis. Parotitis can also be caused by parainfluenza virus types 1 and 3, influenza A virus, Coxsackie A virus, echovirus, lymphocytic choriomeningitis virus, human immunodeficiency virus, and other non-infectious causes such as drugs, tumors, immunologic diseases, and obstruction of the salivary duct.
A: The average incubation period for mumps is 16-18 days, with a range of 12–25 days. Fever may persist for 3–4 days and parotitis, when present, usually lasts 7–10 days.
Persons with mumps are usually considered most infectious from 1-2 days before until 5 days after onset of parotitis.
A: The mumps virus replicates in the upper respiratory tract and is spread through direct contact with respiratory secretions or saliva or through fomites.
A: Severe complications of mumps are rare. However, mumps can cause acquired sensorineural hearing loss in children; incidence is estimated at 1 in 20,000 cases. Mumps-associated encephalitis occurs in < 2 per 100,000 cases and approximately 1% of encephalitis cases are fatal.
Some complications of mumps are known to occur more frequently among adults than among children. Adults have a higher risk for mumps meningoencephalitis than children. In addition, orchitis occurs in up to 30-40% of cases in post pubertal males. Although it is frequently bilateral, it rarely causes sterility. Mastitis has been reported in as many as 31% of female patients older than 15 years who have mumps. Other rare complications of mumps are oophoritis and pancreatitis. Aseptic meningitis occurs in 10% of cases and is associated with a good prognosis. Although mumps infection in the first trimester of pregnancy may result in fetal loss, there is no evidence that mumps during pregnancy causes congenital malformations.
A: Permanent sequelae such as paralysis, seizures, cranial nerve palsies, aqueductal stenosis, and hydrocephalus are rare, as are deaths due to mumps.
A: The following case definition for mumps was updated and approved by the Council of State and Territorial Epidemiologists (CSTE) in 2011.
- Parotitis, acute salivary gland swelling, orchitis, or oophoritis unexplained by another more likely diagnosis, OR
- A positive lab result with no mumps clinical symptoms (with or without epidemiological-linkage to a confirmed or probable case).
- Acute parotitis or other salivary gland swelling lasting at least 2 days, or orchitis or oophoritis unexplained by another more likely diagnosis, in:
- a person with a positive test for serum anti-mumps immunoglobulin M (IgM) antibody, OR
- a person with epidemiologic linkage to another probable or confirmed case or linkage to a group/community defined by public health during an outbreak of mumps.
- A positive mumps laboratory confirmation for mumps virus with reverse transcription polymerase chain reaction (RT-PCR) or culture in a patient with an acute illness characterized by any of the following:
- Acute parotitis or other salivary gland swelling, lasting at least 2 days
- Aseptic meningitis
- Hearing loss
- Page last reviewed: November 12, 2009
- Page last updated: January 12, 2015
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