What blood test is used to diagnose chikungunya?

Blood Tests for Chikungunya Diagnosis

For diagnosing chikungunya virus infection, molecular testing (RT-PCR) should be used during the acute phase (≤7 days after symptom onset), while IgM antibody detection tests are recommended for the convalescent phase (>7 days after symptom onset).

Diagnostic Testing Timeline

Acute Phase (≤7 days after symptom onset)

• RT-PCR (molecular testing): Detects viral RNA directly in serum or plasma
  • Highest sensitivity during first week of infection
  • Provides confirmed evidence of infection with high specificity 1

Convalescent Phase (>7 days after symptom onset)

• IgM antibody detection tests:

  • ELISA-based tests show >90% diagnostic accuracy for samples collected after 7 days 1
  • IgM antibodies begin developing around day 2 but reach detectable levels later
  • Can remain positive for several months (up to 5 months) 2

• IgG antibody detection tests:

  • Show >93% diagnostic accuracy regardless of test format 1
  • Best for samples collected in convalescent phase
  • Useful for determining past infection

Types of Serological Tests

Antigen Detection Tests

• Rapid antigen tests: 85.8% sensitivity, 96.1% specificity 1
• ELISA-based antigen tests: 82.2% sensitivity, 96.0% specificity 1
• Good option for acute phase samples when RT-PCR is unavailable

Antibody Detection Tests

• IgM ELISA:

  • Commercial ELISA tests: >90% accuracy for convalescent samples 1
  • Recombinant capsid protein-based IgM ELISA: 100% sensitivity, 95% specificity 3

• IgM rapid tests:

  • Lower sensitivity (42.3%) compared to ELISA 1
  • Sensitivity increases from 22% in first week to 83% after first week 4
  • Not recommended for screening during first week due to low sensitivity

• Double antigen sandwich ELISA (Das-ELISA):

  • Detects total antibodies against chikungunya
  • 52.5% sensitivity, 96.8% specificity compared to RT-PCR 5
  • 99.5% specificity when compared to immunofluorescence assay 5

Commercial Test Performance

High-performing commercial tests (>90% accuracy) include ELISA-based and immunofluorescence assays from:

• Euroimmun (Lübeck, Germany)
• Abcam (Cambridge, UK)
• Inbios (Seattle, WA) 1

Testing Algorithm

1. Determine time since symptom onset:

   • ≤7 days: Use RT-PCR as primary test

   • 7 days: Use IgM ELISA as primary test

2. If RT-PCR negative but high clinical suspicion:

   • Consider antigen detection test
   • Collect follow-up sample for IgM testing if symptoms persist

3. For definitive diagnosis:

   • Combination of IgM and IgG tests can differentiate between recent and past infections 1

Important Considerations

• Cross-reactivity with other flaviviruses (dengue, Zika) can occur, especially in endemic areas
• Consider testing for multiple arboviruses in endemic regions
• Negative results early in disease course should be interpreted with caution
• Rapid IgM tests have limited utility in the first week of illness

By following this testing approach based on timing of symptom onset, clinicians can maximize diagnostic accuracy for chikungunya virus infection.