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Mumps

(Epidemic Parotitis)

by Mary T. Caserta, MD

Mumps is an acute, contagious, systemic viral disease, usually causing painful enlargement of the salivary glands, most commonly the parotids. Complications may include orchitis, meningoencephalitis, and pancreatitis. Diagnosis is usually clinical; all cases are reported promptly to public health authorities. Treatment is supportive. Vaccination is effective for prevention.

The causative agent, a paramyxovirus, is spread by droplets or saliva. The virus probably enters through the nose or mouth. It is in saliva up to 7 days before salivary gland swelling appears with maximal transmissibility just before the development of parotitis. It is also in blood and urine and, if the CNS is involved, in CSF. One attack usually confers permanent immunity.

Mumps is less communicable than measles. It occurs mainly in unimmunized populations, but outbreaks among largely immunized populations have occurred. A combination of primary vaccine failure (failure to develop immunity after vaccination) and waning immunity may have played a part in these outbreaks. In 2006, there was a resurgence of mumps in the US with 6584 cases, which occurred primarily in young adults with prior vaccination. Two smaller outbreaks occurred in 2009 to 2010, one with 3000 cases, mainly among high school–age people in a religious community in New York City. In the first half of 2014, 871 cases have occurred, many in outbreaks at 4 US universities.

As with measles, mumps cases may be imported, leading to indigenous transmission, especially in congregate settings (eg, college campuses) or closed communities (eg, tradition-observant Jewish communities). Peak incidence of mumps is during late winter and early spring. Disease occurs at any age but is unusual in children < 2 yr, particularly those < 1 yr. About 25 to 30% of cases are clinically inapparent.

Symptoms and Signs

After a 12- to 24-day incubation period, most people develop headache, anorexia, malaise, and a low- to moderate-grade fever. The salivary glands become involved 12 to 24 h later, with fever up to 39.5 to 40° C. Fever persists 24 to 72 h. Glandular swelling peaks on about the 2nd day and lasts 5 to 7 days. Involved glands are extremely tender during the febrile period.

Parotitis is usually bilateral but may be unilateral, especially at the onset. 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. 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.

Complications

Mumps may involve organs other than the salivary glands, particularly in postpubertal patients. Such complications include

  • Orchitis or oophoritis

  • Meningitis or encephalitis

  • Pancreatitis

About 20% of postpubertal male patients develop orchitis (testicular inflammation), usually unilateral, with pain, tenderness, edema, erythema, and warmth of the scrotum. Some testicular atrophy may ensue, but testosterone production and fertility are usually preserved. In females, oophoritis (gonadal involvement) is less commonly recognized, is less painful, and does not impair fertility.

Meningitis, typically with headache, vomiting, stiff neck, and CSF pleocytosis, occurs in 1 to 10% of patients with parotitis (see Overview of Meningitis). Encephalitis, with drowsiness, seizures, or coma, occurs in about 1/1000 to 5000 cases (see Encephalitis). About 50% of CNS mumps infections occur without parotitis.

Pancreatitis, typically with sudden severe nausea, vomiting, and epigastric pain, may occur toward the end of the first week (see Overview of Pancreatitis). These symptoms disappear in about 1 wk, leading to complete recovery.

Prostatitis, nephritis, myocarditis, hepatitis, mastitis, polyarthritis, deafness, and lacrimal gland involvement occur extremely rarely. Inflammation of the thyroid and thymus glands may cause edema and swelling over the sternum, but sternal swelling more often results from submandibular gland involvement with obstruction of lymphatic drainage.

Diagnosis

  • Clinical evaluation

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

  • Serologic testing

Mumps is suspected in patients with salivary gland inflammation and typical systemic symptoms, particularly if there is parotitis or a known mumps outbreak. Laboratory testing is not needed to make a diagnosis but is strongly recommended for public health purposes. Other conditions can cause similar glandular involvement (see Table: Causes of Parotid and Other Salivary Gland Enlargement). Mumps is also suspected in patients with unexplained aseptic meningitis or encephalitis during mumps outbreaks. Lumbar puncture is necessary for patients with meningeal signs.

Causes of Parotid and Other Salivary Gland Enlargement

Suppurative bacterial parotitis

HIV parotitis

Other viral parotitis

Metabolic disorders (eg, uremia, diabetes mellitus)

Mikulicz syndrome (a chronic, usually painless parotid and lacrimal gland swelling of unknown etiology that occurs with TB, sarcoidosis, SLE, leukemia, and lymphosarcoma)

Malignant and benign salivary gland tumors

Drug-related parotid enlargement (eg, due to iodides, phenylbutazone, or propylthiouracil)

Laboratory diagnosis is necessary if disease is

  • Unilateral

  • Recurrent

  • Occurs in previously immunized patients

  • Causes prominent involvement of tissues other than the salivary glands

Testing is also recommended for all patients with 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) and viral culture of the throat, CSF, and occasionally the urine can be done. In previously immunized populations, IgM testing may be falsely negative; therefore, RT-PCR assays should be done on samples of saliva or throat washings as early in the course of the disease as possible.

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. WBC 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.

Prognosis

Uncomplicated mumps usually resolves, although a relapse occurs rarely after about 2 wk. Prognosis of patients with meningitis is usually good, although permanent sequelae, such as unilateral (or rarely bilateral) nerve deafness or facial paralysis, may result. Postinfectious encephalitis, acute cerebellar ataxia, transverse myelitis, and polyneuritis occur rarely.

Treatment

  • Supportive care

Treatment of mumps and its complications is supportive. The patient is isolated until glandular swelling subsides. 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 and support of the scrotum in cotton on an adhesive-tape bridge between the thighs to minimize tension or use of ice packs often relieves pain. Corticosteroids have not been shown to hasten resolution of orchitis.

Prevention

Vaccination with live mumps virus vaccine (see Measles, Mumps, and Rubella Vaccine and see Table: Recommended Immunization Schedule for Ages 0–6 yr) provides effective prevention and causes no significant local or systemic reactions. Two doses, given as a combined measles, mumps, and rubella vaccine, are recommended for children:

  • The first dose at age 12 to 15 mo

  • The second dose at age 4 to 6 yr

Adults born during or after 1957 should have 1 dose, unless they have had mumps diagnosed by a health care practitioner. Pregnant women and people with an impaired immune system should not be given such live-attenuated vaccines.

Postexposure vaccination does not protect against mumps from that exposure. Mumps immune globulin is no longer available, and serum immune globulin is not helpful. The Centers for Disease Control and Prevention now recommend isolation of infected patients with standard and respiratory droplet precautions for 5 days after the onset of parotitis. Susceptible contacts should be vaccinated, but this intervention is unlikely to abort an outbreak in progress. Nonimmune asymptomatic healthcare providers should be excused from work from 11 days after the initial exposure until 25 days after the last exposure.

Key Points

  • Mumps causes painful enlargement of the salivary glands, most commonly the parotids.

  • Cases may occur in vaccinated people because of primary vaccination failure or waning immunity.

  • About 20% of infected postpubertal males develop orchitis, usually unilateral; some testicular atrophy may occur, but testosterone production and fertility are usually preserved.

  • Other complications include meningoencephalitis and pancreatitis.

  • Laboratory diagnosis is done mainly for public health purposes and when disease manifestations are atypical, such as absence of parotitis, unilateral or recurrent parotitis, parotitis in previously immunized patients, or prominent involvement of tissues other than the salivary glands.

  • Universal vaccination is imperative unless contraindicated (eg, by pregnancy or severe immunosuppression).

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