What are the recommended diagnostic tests for mumps?

Diagnostic Tests for Mumps

The recommended diagnostic approach for mumps includes serologic testing for mumps-specific IgM and IgG antibodies, along with viral detection through RT-PCR or culture from buccal swabs collected from the parotid (Stensen) duct area. 1

Primary Diagnostic Methods

Serologic Testing

• Antimumps IgM antibodies:

  • First-line test for acute infection
  • Becomes detectable during first few days of illness
  • Peaks approximately 1 week after symptom onset
  • May remain detectable for several months 1
  • Collection: Serum in clot or serum separator tube at room temperature, transported within 2 hours

• Antimumps IgG antibodies:

  • Acute and convalescent phase testing to demonstrate seroconversion or 4-fold rise in titer
  • Acute sample: Collect immediately upon symptom onset
  • Convalescent sample: Collect 5-10 days later 1
  • Presence indicates immunity to mumps

Viral Detection Methods

• RT-PCR (NAAT):

  • Preferred specimen: Buccal/parotid (Stensen) duct swab 1
  • Collection technique: Massage parotid gland for 30 seconds, then swab parotid duct
  • Transport in viral transport medium at room temperature within 2 hours
  • Can detect virus prior to parotitis onset until 5-9 days after symptoms begin
  • Critical for previously vaccinated patients who may not develop IgM response 1

• Viral Culture:

  • Same specimen collection as RT-PCR
  • Less commonly available (often limited to public health laboratories)
  • Transport on wet ice when possible 1

Important Clinical Considerations

Special Populations

• Previously vaccinated individuals:
  • May not develop detectable IgM response despite active infection 1
  • Viral detection methods (PCR/culture) are essential for diagnosis in these cases
  • Consider IgA testing as it may increase diagnostic yield in vaccinated populations 2

Specimen Timing and Collection

• Optimal timing:

  • Serology: As soon as mumps is suspected
  • Viral detection: Prior to onset of parotitis until 5-9 days after symptom onset
  • Urine samples are less sensitive and virus may not be detected until ≥4 days after symptom onset 1

• Alternative specimens:

  • CSF: For suspected mumps meningitis (collect in sterile tube)
  • Oropharyngeal swabs: Secondary option when parotid swab not possible
  • Urine: Lower sensitivity but can be collected in sterile container 1

Diagnostic Algorithm

1. Initial presentation with parotitis:

   • Collect serum for IgM and IgG testing
   • Obtain parotid (Stensen) duct/buccal swab for RT-PCR and/or culture
   • Massage parotid gland before swabbing to increase yield

2. For previously vaccinated patients:

   • Prioritize RT-PCR testing from parotid swab
   • Consider IgA testing if available
   • If initial IgM is negative but clinical suspicion remains high, collect convalescent serum

3. For suspected mumps meningitis:

   • Add CSF collection for IgM, PCR and culture

Common Pitfalls and Caveats

• Relying solely on IgM serology may miss cases, especially in vaccinated individuals 1, 3
• Clinical diagnosis without laboratory confirmation may lead to misdiagnosis as other conditions can cause parotitis 1
• Single serologic tests may be negative in patients with clinically apparent mumps; timing of testing is critical 3
• Parainfluenza virus infections may cause low cross-reactive antimumps IgG antibody titers 4

Reporting Requirements

• Probable or confirmed mumps cases should be reported immediately to state and local health departments 1
• Laboratory confirmation is preferred due to other potential causes of parotitis 1