• Clinical science

Mumps

Abstract

Mumps is a highly contagious viral infection that is transmitted via airborne droplets. The incidence is now very low in the US because of the combined measles, mumps, and rubella (MMR) vaccine. The condition primarily affects children between the ages of five and fourteen. Classically, it manifests with parotitis, which initially occurs unilaterally, but typically progresses to involve both sides. The lateral cheek and jaw area usually show marked swelling and the ears may protrude. Other symptoms include low-grade fever, malaise, headache, and possible swelling of other salivary glands. The diagnosis of mumps is largely based on clinical findings. Many cases, however, present with nonspecific features and are not easily recognizable as mumps. If possible, diagnosis should be confirmed with laboratory tests. Treatment is symptomatic. Rare complications include orchitis, aseptic meningitis, deafness, and pancreatitis. Immunization offers the best protection against future exposure. Mumps is a self-limiting disease, followed by lifelong immunity. The prognosis in uncomplicated cases is very good.

Epidemiology

  • Sex: = for parotitis (however, males are three times more likely to have CNS complications)
  • Peak incidence: 5–14 years of age
  • The incidence in the United States has drastically declined since administration of the MMR vaccine became routine.

References:[1][2][3][4]

Epidemiological data refers to the US, unless otherwise specified.

Etiology

  • Pathogen: Mumps virus; from the family Paramyxoviridae
    • Humans are the sole hosts
  • Transmission
    • Airborne droplets
    • Direct contact with contaminated saliva or respiratory secretions
    • Contaminated fomites
  • Infectivity:
    • Highly infectious
    • Affected individuals are contagious ∼ 3 days before and up to 9 days after disease onset (when the parotid gland becomes swollen).

Asymptomatic cases are also contagious!

References:[3][5]

Pathophysiology

References:[3]

Clinical features

  • Incubation period: 16–18 days
  • Asymptomatic course in ∼ 20% of cases
  • Nonspecific or predominantly respiratory symptoms in ∼ 50% of cases
  • Prodrome:
  • Classic course (in ∼ 30% of cases):inflammation of the salivary glands, particularly parotitis
    • Duration of parotitis: at least 2 days (may persist > 10 days)
    • May initially present with local tenderness, pain, and earache
    • Swelling on one side is initially observed. During the course of disease, both salivary glands are usually swollen.
      • Possible redness in the area of the parotid duct
      • Possible protruding ears
    • Usually self-limiting with a good prognosis (unless complications arise)
    • Chronic courses are rare

References:[1][5][6]

Diagnostics

Laboratory tests, if available, should be conducted to confirm the suspected cases (especially if presentation is atypical or there is a mumps outbreak).

References:[3][7][8][9]

Differential diagnoses

Differential diagnosis of parotid swelling

Mumps Acute purulent sialadenitis Sialadenosis (sialosis) Sialolithiasis (salivary stones) Tumors of the salivary glands
Findings
  • Possible redness, tenderness and protruding ears
  • Usually bilateral
  • Fever
  • Fever, tenderness, and swelling of the gland
  • Usually unilateral
  • Possible pus discharge
  • Sudden pain while eating
  • Partial swelling of the gland
  • Painless swelling of the gland
  • Possible malignant symptoms of infiltrated structures (e.g., facial palsy)

References:[10][11][12]

The differential diagnoses listed here are not exhaustive.

Treatment

  • Symptomatic therapy
    • Medication for pain and fever (e.g., acetaminophen)
    • Bedrest
    • Adequate fluid intake
    • Avoidance of acidic foods and drinks
    • Ice packs to soothe parotitis
    • Isolation and post-exposure prophylaxis → see “Prevention” below

References:[3]

Complications

  • Orchitis (< 10% of cases; most common complication in post-pubertal males)
    • Primarily unilateral, although bilateral in ∼ 15% of cases
    • Sudden onset of fever, nausea, vomiting
    • On examination: swollen and tender affected testicle(s)
    • May lead to atrophy and, in rare cases, infertility
  • Acute pancreatitis (< 1% of cases)
  • Aseptic meningitis (< 1% of cases); : predominantly mild course
  • Meningoencephalitis (< 1% of cases)

References:[13][3][7]

We list the most important complications. The selection is not exhaustive.

Prevention

  • Primary immunization: a live vaccine in combination with measles and rubella vaccine (i.e., MMR) and, if necessary, varicella (MMRV)
  • Postexposure prophylaxis
    • Indication: negative or ambiguous serology (absence of prior infection or vaccination); patients born before 1957 (especially indicated during a mumps outbreak)
    • Active immunization: ideally with the MMR vaccine

Mumps vaccination during the first trimester in pregnancy may lead to embryonal death!

  • Isolate infected patients (up to 5 days after onset of symptoms)
  • Mumps is a reportable disease

References:[1][3][7][8][14]