Description

• Painful parotitis occurs in 95% of symptomatic mumps, but 1/3 of mumps cases may be asymptomatic.
• Epidemics in late winter and spring, with transmission by respiratory secretions
• Incubation ∼14–24 days
• System(s) affected: Hematologic/Lymphatic/Immunologic; Reproductive; Skin/Exocrine
• Synonym(s): Epidemic parotitis; Infectious parotitis

Epidemiology

• Predominant age: 85% occur before age 15:
  • Adult cases typically more severe
• Predominant sex: Male = Female
• Geriatric population: Most are immune.
• Acute epidemic mumps:
  • Most cases occur in children aged 5–15 years.
  • Recent (2006) US epidemic in vaccinated college students aged 18–24 years with 5,700 US cases:
    • Another US epidemic 2009–2010 in NY/NJ, >1,500 cases (1)
  • Unusual in children <2 years of age
  • Most infants <1 year are immune.
  • Urban epidemics among nonvaccinated populations
  • Communicable period 24 hours before to 72 hours after parotitis onset
  • Incubation period 18 days

• 0.09/100,000 persons in the US
• Occasional epidemic outbreaks in a given region

• 0.0064/100,000 persons
• 90% of adults are seropositive even without history.

Risk Factors

• Foreign travel/exposure: 43% of other nations do not vaccinate for mumps.
• Crowded environments such as dormitories
• Waning immunity after single-dose vaccination:
  • After 2 doses, immunity drops from 95% to 86% in 9 years (2)[C].

General Prevention

• Vaccination:
  • 2 doses of live mumps vaccine or measles-mumps-rubella (MMR) vaccine recommended, 1st at 12–15 months and 2nd at 4–6 years of age
  • 95% effective in studies, but field trials show 75–95% efficacy, which may be below level needed for herd immunity to prevent epidemic spread (3)[C].
  • Successful prevention (Finland) may require 95% 1st-dose plus >80% 2nd-dose compliance (4).
  • Adverse effects: Most common proven effect is ITP, with incidence of 3.3/100,000 doses.
  • No relationship between MMR vaccine and autism (5)[A]
• Immunoglobulin is not effective in prevention.
• Postexposure vaccination does not protect from recent exposure.
• Isolate hospitalized patients until 5 days past onset (6)[C].
• Exclude nonimmune individuals for 26 days after last case onset.

• There are no proven complications of vaccine, but theoretically one should not vaccinate in pregnancy.
• Immunization of family may protect against later exposures but not the present one.

Pathophysiology

Mumps virus replicates in glandular epithelium of parotids, pancreas, and testes:

• Leads to interstitial edema and inflammation
• Interstitial glandular hemorrhage may occur.
• Pressure caused by edema of the testes against the tunica albuginea can lead to necrosis.

Etiology

• Mumps paramyxovirus
• Other viruses, such as coxsackievirus (rare)