Mumps/Parotitis

Basics

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

Incidence

  • 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.
  • 200–300 cases per year reported in the United States since 2001
  • In early 2006, a large epidemic broke out in Iowa and neighboring states:
    • 11 states reported >2,500 cases.
    • Largest epidemic since 1988
    • Median age of patient was 21 years (mostly college students)
    • Led CDC and American College Health Association to recommend 2 doses of MMR vaccine to be a requirement for college entry
  • In 2006, 81–100% of children entering United States schools had received 2 doses of mumps vaccine.
  • In 2009–2010, an outbreak of mumps occurred in a highly vaccinated population in the northeastern United States. Intense exposure facilitated transmission. Previous vaccination appeared to limit the severity of disease.
  • Seroprevalence of antibody to mumps virus in the United States population (1999–2004) is estimated at 90%.

General Prevention

  • 2 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 12–15 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.
  • Some have suggested the need for a 3rd vaccination to mitigate waning immunity. Preliminary studies indicate no increase in adverse effects after a 3rd vaccination.
  • The 1st dose of MMR vaccine sometimes causes fever and rash:
    • These symptoms occur 7–12 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 5–12 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, administration of MMR vaccine should be delayed (for 3–11 months depending on the dose of IG).
  • Children with HIV infection who are not severely immunocompromised should be immunized with the MMR vaccine.
  • 1 attack of mumps (clinical or subclinical) usually confers lifelong immunity.
  • Links of the MMR vaccine to autism by Andrew Wakefield MB, BS in a 1998 Lancet publication have now been exposed as fraudulent.

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: 2–3 days before to 5 days after onset of parotid swelling
  • Incubation period: 12–25 days after exposure
  • Humans are the only known host for mumps.

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).

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 4–10 days of the onset of the parotid swelling.
    • Sterility is uncommon.
  • Aseptic meningitis
  • Pancreatitis
    • Mild inflammation is common.
    • Serious involvement is rare.

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