Mumps

After a 12- to 25-day incubation period (most commonly 16 to 18 days), most people develop headache, anorexia, malaise, myalgia, and a low- to moderate-grade fever. Approximately 20 to 30% of unvaccinated people are asymptomatic (1, 2). Symptoms and severity of illness are reduced in people who are vaccinated (1).

Glandular swelling peaks on about the 2nd day and lasts 5 to 7 days. Parotitis may be unilateral or bilateral; however, in initially unilateral cases, the contralateral parotid gland is eventually involved 70% of the time) (1, 3). Involved glands are extremely tender during the febrile period. In some instances, parotitis may emerge within weeks or months after apparent recovery.

Mumps (1)

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This image shows a child with right-sided parotid swelling due to mumps parotitis, obscuring the angle of the mandible. Parotitis also characteristically causes lifting of the earlobe upward and outward, which is best viewed by standing behind the patient.

Image courtesy of Sylvan Stool, MD.

Mumps (2)

Image

This image shows left-sided parotid swelling due to mumps parotitis in an unvaccinated 2-year-old child.

DR P. MARAZZI/SCIENCE PHOTO LIBRARY

Pain while chewing or swallowing, especially while swallowing acidic liquids such as vinegar or citrus juice, is its earliest symptom. It later causes swelling beyond the parotid in front of and below the ear. Parotitis also characteristically causes displacement of the earlobe upward and outward, which is best viewed by standing behind the patient.

Occasionally, the submandibular and sublingual glands also swell and, more rarely, are the only glands affected. Submandibular gland involvement causes neck swelling beneath the jaw, and suprasternal edema may develop, perhaps because of lymphatic obstruction by enlarged salivary glands. When sublingual glands are involved, the tongue may swell. The oral duct openings of the affected glands are edematous and slightly inflamed. The skin over the glands may become tense and shiny.

• History of exposure (particularly if unvaccinated) and characteristic symptoms (eg, fever, headache, anorexia, malaise, myalgia)

• Physical examination with unilateral or bilateral enlarged parotid glands

• Viral detection via reverse transcription–polymerase chain reaction (RT-PCR)

• Serologic testing

Mumps is suspected in patients with evidence of salivary gland inflammation and typical systemic symptoms, particularly if there is parotitis or a known mumps outbreak. Laboratory testing is usually not needed to make a diagnosis in typical cases but is strongly recommended for public health purposes.

Mumps is also suspected in patients with unexplained aseptic meningitis or encephalitis during mumps outbreaks. Lumbar puncture is necessary for patients with meningeal signs.

Both mumps-specific IgM testing and RT-PCR may be used for diagnostic purposes; however, RT-PCR is preferred in vaccinated patients because IgM response may be transient or nondetectable after vaccination (1). The preferred specimen for RT-PCR is a buccal swab after parotid gland massage (2, 3).

Differential diagnosis includes other conditions that can cause similar glandular involvement (see table Non-Mumps Causes of Parotid and Other Salivary Gland Enlargement).

Laboratory diagnosis of mumps is necessary if disease has features atypical for mumps such as the following:

• Unilateral

• Recurrent

• Occurs in previously immunized patients

• Causes prominent involvement of tissues other than the salivary glands

• Parotitis lasting ≥ 2 days without an identified cause

RT-PCR is the preferred method of diagnosis; however, serologic testing of acute and convalescent sera by complement fixation or enzyme-linked immunosorbent assays (ELISA) can be performed. In previously immunized patients, IgM testing may be falsely negative; therefore, RT-PCR assays should be performed on samples of saliva or throat washings as early in the course of the disease as possible (1, 4).

Other laboratory tests are generally unnecessary. In undifferentiated aseptic meningitis, an elevated serum amylase level can be a helpful clue in the diagnosis of mumps despite the absence of parotitis. White blood cell count is nonspecific; it may be normal but usually shows slight leukopenia and neutropenia.

In meningitis, CSF glucose is usually normal but is occasionally between 20 and 40 mg/dL (1.1 and 2.2 mmol/L), as in bacterial meningitis. CSF protein is only mildly elevated.

• Isolation

• Supportive care

Patients are isolated for 5 days at onset of parotitis or at onset of their first symptom if they do not develop parotitis (1).

Treatment of mumps and its complications is supportive.

A soft diet reduces pain caused by chewing. Acidic substances (eg, citrus fruit juices) that cause discomfort should be avoided.

Repeated vomiting due to pancreatitis may necessitate IV hydration.

For orchitis, bed rest with elevation and support of the scrotum by using a commercial scrotal supporter, a folded towel, or an adhesive-tape bridge between the thighs to minimize tension. Ice packs often relieve pain. Glucocorticoids have not been shown to hasten resolution of orchitis and may decrease testosterone concentration, facilitating testicular atrophy and potentially increasing the risk of infertility (2, 3).

Uncomplicated mumps usually resolves, although, rarely, a relapse occurs after about 2 weeks.

Although infertility is rare in males with mumps orchitis, testicular atrophy has been reported in up to 50%, and abnormal sperm count, morphology, or motility in 25% (1). The incidence of infertility in females with mumps oophoritis not well characterized.

Prognosis for patients with meningitis is usually good, although permanent sequelae, such as unilateral (or rarely bilateral) nerve deafness or facial paralysis, may result. Mumps is thought to be a major cause of acquired sensorineural hearing loss in children in parts of the world where vaccination rates are low (2).

Postinfectious encephalitis, acute cerebellar ataxia, transverse myelitis, and polyneuritis occur rarely.

Vaccination with live-attenuated virus vaccine containing measles, mumps, and rubella (MMR) is administered routinely to children in most nations that have a robust health care system. In the United States, the MMR vaccine is recommended for children and is administered in 2 doses: 1 at age 12 to 15 months and 1 at age 4 to 6 years.

A large meta-analysis of cohort studies found the effectiveness of the MMR vaccine in preventing mumps in children from age 9 months to 15 years was 72% after 1 dose and 86% after 2 doses (1). However, immunity to mumps after vaccination may wane over time (2).

MMR is a live vaccine and is contraindicated during pregnancy. It is also contraindicated in certain immunocompromised patients and in patients who have had an anaphylactic reaction to a vaccine component or previous vaccine dose (3).

See MMR Vaccine for more information, including indications, contraindications and precautions, dosing and administration, and adverse effects.

Postexposure vaccination does not protect against mumps from that exposure. Mumps immune globulin is not available, and serum immune globulin is not helpful (4).

The CDC recommends isolation of infected patients with standard and respiratory droplet precautions for 5 days after the onset of parotitis (5). Susceptible contacts should be vaccinated, and a third dose is recommended for previously immunized people at increased risk of mumps during an outbreak, as determined by public health officials. Robust data are lacking, but a third dose and additional measures may help control an outbreak (6). Nonimmune asymptomatic health care professionals should be excused from work from 12 days after the initial exposure through 25 days after the last exposure.