Description

Centers for Disease Control and Prevention (CDC) clinical case definition for mumps: illness with acute onset of unilateral or bilateral, tender, self-limited swelling of the parotid or other salivary gland, lasting ≥2 days, without other apparent cause

Epidemiology

• In the prevaccine era, 90% of all children contracted mumps virus infection by 14 years of age.
• Incidence of this once very common disease has declined dramatically since the advent of universal childhood immunization.
• Outbreaks, however, continue to occur, and cases in the United States have ranged from several hundred to several thousand cases annually.
• Since 2014, >1,000 cases per year have been reported in the United States, with >6,000 cases reported in 2016.
• Most outbreaks have been linked to being in a close crowded environment and intense exposures, such as universities, sports teams, and close-knit religious communities.
• Outbreaks can occur in highly vaccinated communities, particularly in very close-contact settings such as college dormitories and camps.
• High vaccination rate helps limit the severity, size, and duration of mumps outbreaks.

General Prevention

• Two combination mumps vaccine are used:
  • MMR: measles, mumps, rubella
  • MMRV: measles, mumps, rubella, varicella
• A single 0.5-mL SC injection of live mumps vaccine (MMR or MMRV) is recommended at 12 to 15 months.
• A second vaccination is recommended between 4 and 6 years of age.
• The efficacy of 2 doses of vaccines is estimated at approximately 80–90%.
• Primary vaccine failure and waning vaccine-induced immunity have been reported.
• During mumps outbreaks, a third dose of vaccine may be recommended by public health authorities for targeted populations in conjunction with CDC guidance. Studies indicate no increase in adverse effects after a third vaccine dose and improved control of mumps outbreak.
• The first dose of MMR vaccine can be associated with fever and rash:
  • These symptoms occur 7 to 12 days after immunization.
  • Measles component is usually the culprit.
• Both MMRV and MMR vaccines, but not varicella vaccine alone, are associated with increased outpatient fever visits and seizures 5 to 12 days after vaccination in 12- to 23-month-olds, with MMRV vaccine increasing fever and seizure twice as much as the MMR + varicella vaccine.
• Vaccine should not be administered to children who are immunocompromised by disease or pharmacotherapy, as well as to pregnant women.
• If a child has recently received immune globulin (IG), administration of MMR vaccine should be delayed (for 3 to 11 months depending on the dose of immune globulin).
• Children with HIV infection who are not severely immunocompromised (age-specific CD4+ T-lymphocyte percentages of 15% or greater) should be immunized with the MMR vaccine.
• One attack of mumps (clinical or subclinical) usually confers lifelong immunity.
• Links of the MMR vaccine to autism by Andrew Wakefield in a 1998 Lancet publication have now been exposed as fraudulent, and multiple studies have documented no association between MMR vaccine and autism.

Etiology

• Epidemic parotitis is caused by mumps, an RNA virus in the Paramyxoviridae family.
• Other viral causes of parotitis include Epstein-Barr virus, cytomegaloviruses, influenza, parainfluenza, and enteroviruses.
• Parotid enlargement can be an initial sign in HIV-infected children.
• Bacterial cases are usually secondary to Staphylococcus aureus (suppurative parotitis).
• Streptococci, gram-negative bacilli, and anaerobic infections are also possible.
• Rare childhood cases may be secondary to an obstructing calculus, foreign body (sesame seed), tumors, sarcoid, Sjögren syndrome, or various drugs (antihistamines, phenothiazines, iodine-containing drugs/contrast media).

Pathophysiology

• The virus is spread by contact with respiratory secretions.
• The mumps virus enters via the respiratory tract, and a viremia ultimately ensues.
• The virus spreads to many organs, including the salivary glands, gonads, pancreas, and meninges.
• Period of communicability: 7 days before to 9 days after onset of parotid swelling
• Most communicable period: 2 to 3 days before to 5 days after onset of parotid swelling
• Incubation period: 12 to 25 days after exposure (16 to 18 days most common)
• Humans are the only known host for mumps.

Commonly Associated Conditions

• Salivary adenitis
  • Most common manifestation of mumps
  • 1/3 of cases occur subclinically.
• Epididymoorchitis
  • Up to 35% of adolescent mumps cases are complicated by orchitis.
  • Orchitis develops within 4 to 10 days of the onset of the parotid swelling.
  • Sterility is uncommon.
• Aseptic meningitis
• Pancreatitis
  • Mild inflammation is common.
  • Serious involvement is rare.

History

• Prodromal symptoms uncommon but may include the following:
  • Fever
  • Anorexia
  • Myalgia
  • Headache
• Onset usually pain and swelling in front of and below ear
• Swelling
  • Usually starts on one side of the face, then progresses to the other
• Mild fever
  • Usually accompanies parotid swelling
• Dysphagia and dysphonia are common.
• Testicular pain and swelling, along with constitutional symptoms, occurs in postpubertal males usually 1 week after parotid swelling but occasionally simultaneously or alone.
• Epigastric pain and constitutional symptoms with pancreatic involvement
• Fever, headache, and stiff neck with meningitis
• Behavioral changes, seizures, and other neurologic abnormalities are rare.
• Other symptoms are analogous to the particular organ involved.

Physical Exam

• Nonerythematous, tender parotid swelling (erythema suggests suppurative parotitis)
• Swelling ultimately obscures the mandibular ramus.
• The ear is displaced upward and outward.
• Importantly, up to 30% of symptomatic cases of mumps are not associated with parotitis.
  • These may manifest only with upper respiratory tract symptoms.
• Submaxillary and sublingual glands also may be swollen.
• Inflammation may be noted intraorally at the orifice of Stensen duct.
• Presternal edema is occasionally noted.
• Mumps are infrequently associated with truncal rash.
• Tender, edematous testicle in mumps orchitis (usually unilateral)
• Ask the patient if the pain (at the parotid) intensifies with the tasting of sour liquids:
  • Have the patient suck on a lemon drop or lemon juice and note any discharge from Stensen duct.

Differential Diagnosis

• Mumps parotitis can be distinguished from the other viral causes by clinical presentation along with specialized laboratory studies.
• Cases of tuberculous and nontuberculous (atypical) mycobacterial parotitis are rare but have been reported.
• Salivary calculus can be diagnosed by sialogram.
• Recurrent childhood parotitis, also known as juvenile recurrent parotitis
  • Rare, recurrent swelling of parotids
  • Seen in children 3 to 6 years old
  • Not associated with suppuration or external inflammatory changes
  • Largely a diagnosis of exclusion
• Cervical or preauricular adenitis
  • May simulate parotitis
  • Close anatomic localization should be diagnostic.
• Infectious mononucleosis and cat-scratch disease are other considerations.
• Drug-induced parotid enlargement occasionally occurs.
• Malignancies of the parotid are extremely rare.
• Sjögren syndrome is rare but reported in children.
• Pneumoparotitis is seen in those with a history of playing a wind instrument, glass blowing, scuba diving, and even general anesthesia.

Diagnostic Tests and Interpretation

• Uncomplicated parotitis
  • Mild leukopenia with lymphocytosis
• Suppurative parotitis and mumps orchitis
  • Leukocytosis
• Pancreatic involvement
  • Hyperamylasemia and elevated serum lipase
• Salivary adenitis without pancreatic involvement
  • Isolated hyperamylasemia
• Gram stain and culture of pus expressed from Stensen duct is diagnostic in suppurative parotitis.
• CDC lab criteria for mumps diagnosis
  • Isolation of mumps virus from clinical specimens: blood, urine, buccal swab (Stensen duct exudates), throat washing, saliva, or CSF
  • Detection of mumps virus nucleic acid by reverse transcriptase PCR
  • Obtain specimens for culture and PCR as soon as possible after onset of symptoms, particularly in vaccinated individuals.
  • Positive serologic test for mumps IgM
  • Significant rise between acute and convalescent titers in mumps IgG levels by any standard assay (complement fixation, neutralization, hemagglutination inhibition, or enzyme immunoassays)
  • For detailed information regarding collection and interpretation of laboratory studies and mumps case reporting, see http://www.cdc.gov/mumps/.
• Sialography is useful to evaluate for stones or strictures but is contraindicated in acute infection.
• Lumbar puncture if meningitis is suspected: CSF pleocytosis (predominately mononuclear)

General Measures

• Supportive therapy is all that is required in mumps parotitis.
• Antibiotics directed against S. aureus should be used in cases of suppurative parotitis.

Follow-Up Recommendations

• Most children have resolution of glandular swelling by ~1 week.
• Disappearance of testicular pain and swelling can be expected 4 to 6 days after onset.
• Testicular atrophy is common, although infertility is rare.
• Markedly elevated pancreatic enzymes should be monitored until they improve.
• Children should not return to school until at least 5 days after the onset of parotid swelling.
• Isolation: standard precautions; droplet precautions for 5 days after onset of parotid swelling

Prognosis

Complete recovery in 1 to 2 weeks is the rule.

Complications

• Meningitis
  • >50% have a CSF pleocytosis.
  • This “aseptic meningitis” is usually benign.
• Encephalitis: rarely causes permanent sequelae
• Cerebellitis
• Facial nerve palsy
• Oophoritis, nephritis, thyroiditis, myocarditis, mastitis, arthritis, transient ocular involvement, deafness, and sterility (all rare)

ICD-9

• 072.9 Mumps without mention of complication
• 072.79 Other mumps with other specified complications
• 072.0 Mumps orchitis
• 072.3 Mumps pancreatitis
• 072.1 Mumps meningitis
• 072.2 Mumps encephalitis
• 072.71 Mumps hepatitis
• 072.72 Mumps polyneuropathy
• 072.8 Mumps with unspecified complication

ICD-10

• B26.9 Mumps without complication
• B26.89 Other mumps complications
• B26.0 Mumps orchitis
• B26.3 Mumps pancreatitis
• B26.2 Mumps encephalitis
• B26.81 Mumps hepatitis
• B26.84 Mumps polyneuropathy
• B26.83 Mumps nephritis
• B26.82 Mumps myocarditis
• B26.85 Mumps arthritis
• B26.1 Mumps meningitis

SNOMED

• 36989005 Mumps (disorder)
• 240526004 Mumps parotitis
• 78580004 mumps orchitis (disorder)
• 10665004 mumps pancreatitis (disorder)
• 63462008 mumps myocarditis (disorder)
• 17121006 Mumps nephritis (disorder)
• 44201003 Mumps meningitis (disorder)
• 31524007 mumps polyneuropathy (disorder)
• 31646008 Mumps encephalitis