Mumps

Aka: Mumps, Epidemic Parotiditis, Epidemic Parotitis

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II. Epidemiology

  1. Peak Age 10-19 years
  2. Incidence
    1. U.S. Cases in 1968: 152,000 cases
    2. U.S. Cases in 2000: 338 cases
    3. U.S. Cases in 2015: 1057 cases

III. Pathophysiology

  1. Caused by a paramyxovirus
  2. Transmission
    1. Transmitted easily by airborne droplet spread (Saliva or nasal secretions)
    2. Also transmitted in urine
  3. Incubation: 12-25 days (typically 16-18 days)
  4. Infectious:
    1. Start: 6 days before Parotitis
    2. Ends: 2 weeks after symptom onset

IV. Symptoms

  1. Subclinical presentation in 20-40% of cases
  2. Prodrome (onset after 12-25 day Incubation Period)
    1. Fever (moderate, lasts 7 days)
    2. Malaise
    3. Headache
    4. Anorexia
    5. Myalgias
  3. Sudden onset pain, swelling, tenderness in cheeks at Parotid Gland lasting >2 days
    1. Starts as unilateral and becomes bilateral in 90% of cases
    2. Provoked by chewing or Swallowing
    3. Worse with sour foods or acidic foods
  4. Associated Symptoms
    1. Otalgia
    2. Trismus

V. Signs

  1. Sialadenitis
    1. Parotitis occurs in 30-40% of patients
    2. Tender swelling of all Salivary Glands in 10% of cases
    3. Typically bilateral involvement (but may start unilaterally)
    4. Skin over Parotid Gland not warm or red
      1. Contrast with Bacterial Sialadenitis
    5. Tenderness and swelling at mandibular angle (may obscure angle of jaw)
    6. Parotid duct (Stensen duct) opening appears red and edematous in Buccal mucosa
  2. Orchitis (3-10% of postpubertal males, up to 40% of males overall)
    1. Occurs 7-10 days after Parotitis
  3. Maculopapular rash
    1. Variably present
    2. May develop over the trunk

VI. Complications

  1. Orchitis (see signs as above)
    1. Testicular Atrophy (50%)
    2. Bilateral Orchitis in 30% of cases
    3. Infertility
      1. Highest risk if bilateral involvement
  2. Pancreatitis (usually uncomplicated)
  3. Central Nervous System Involvement
    1. Asymptomatic Cerebrospinal Fluid Leukocytosis (50%)
    2. Less common causes
      1. Encephalitis (1 case per 400 to 6000 Mumps cases)
        1. Mortality: 1-2% death rate from Encephalitis
        2. Consider for high fever, Headache, neck stiffness or Seizures
      2. Aseptic Meningitis
        1. Typically benign, but some will develop other neurologic complications
      3. Paralytic Polio-like syndrome
      4. Transverse Myelitis
      5. Cerebellar Ataxia
  4. Miscellaneous
    1. Deafness (<1% in the post-Vaccine era)
    2. Oophoritis (ovarian inflammation)
    3. Subacute Thyroiditis
    4. Dacryoadenitis
    5. Optic Neuritis
    6. Iritis
    7. Conjunctivitis
    8. Myocarditis
    9. Hepatitis
    10. Nephritis
    11. Mastitis
    12. ThrombocytopeniaPurpura
    13. Interstitial Pneumonia
    14. Migratory polyarthritis

VII. Labs

  1. Complete Blood Count
    1. Parotitis: Relative Lymphocytosis
    2. Orchitis: Marked Leukocytosis
  2. Serum Amylase increased
  3. Cerebrospinal Fluid
    1. White Blood Cells: 1000-2000 with Neutrophils

VIII. Diagnosis: Culture, IgG, and IgM should all be done

  1. Mumps PCR
  2. Culture
    1. Obtain sample within first 5 days of Parotitis
    2. Blood, Throat, CSF, Urine
    3. Immunofluorescence positive in 2-3 days
  3. Serology
    1. Mumps IgM
      1. Positive after day 3 of swelling
      2. Titers peak by one week
    2. Mumps IgG
      1. Obtain acute baseline Mumps IgG as soon as possible
      2. Check Mumps IgG again 3-5 weeks after onset
      3. Titer increases 4 fold

IX. Management

  1. Orchitis
    1. Scrotal support
    2. NSAIDs
    3. Consider Interferon alpha 2b
      1. Reduces testicular atrophy and Infertility risk
  2. Intravenous Immunoglobulin (IVIG) Indications
    1. Guillain-Barre Syndrome
    2. Idiopathic Thrombocytopenia
    3. Post-Infectous Encephalitis
  3. Consider MMR Vaccine dose for contagious contacts who have been previously vaccinated (2 prior MMR doses)
    1. Consider third dose MMR Vaccine which may help prevent mumps infection during an outbreak
    2. Immunoglobulin is not effective for Post-exposure Prophylaxis
  4. Suspected cases
    1. Report to local public health department
    2. Follow standard isolation with droplet precautions (respiratory and Saliva sources) while in hospital
    3. Quarantine patient for 2 days before until 5 days after parotid swelling onset

X. Prevention

  1. MMR Vaccine
    1. MMR Vaccine is contraindicated in pregnancy and Immunocompromised patients (Live Vaccine)
    2. MMR Vaccine is indicated for all children in U.S. at 12-15 months and 4-6 years
    3. Effective at preventing mumps in 88% of immunized patients (78% after the first dose)
    4. Antibody levels wane over time (esp. elderly), and may present atypically with mumps

XI. Prognosis

  1. Mortality: Up to 50 deaths per 1 million Mumps cases

XII. Resources

  1. CDC Mumps
    1. http://www.cdc.gov/vaccines/pubs/pinkbook/downloads/mumps.pdf
  2. Medscape EMedicine
    1. http://reference.medscape.com/article/966678-overview

XIII. References

  1. Harrison and Ruttan (2019) Crit Dec Emerg Med 33(7): 3-12
  2. Spencer (2017) Am Fam Physician 95(12): 786-94 [PubMed]

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