Dengue Virus Antibody Test (IgM/IgG)
🦟 Dengue Virus Antibody (IgM/IgG) Test: Complete Medical Guide
Pathophysiology · ELISA Method · Interpretation · Clinical Use
1. Overview of the Dengue Virus
✔ Virology
- Family: Flaviviridae
- Type: Single-stranded RNA virus
- Serotypes: DENV-1, DENV-2, DENV-3, DENV-4
- Infection by one serotype provides lifelong immunity only to that subtype.
- Secondary infection with another serotype increases risk of DHF (Dengue Hemorrhagic Fever) and DSS (Dengue Shock Syndrome) due to antibody-dependent enhancement (ADE).
✔ Transmission
- Spread by Aedes aegypti and Aedes albopictus
- Human → mosquito → human transmission cycle
✔ Clinical Manifestations
- High fever
- Severe myalgia (“breakbone fever”)
- Retro-orbital pain
- Rash
- Thrombocytopenia
- Warning signs: abdominal pain, mucosal bleeding, plasma leakage
- Severe forms: DHF, DSS
2. Purpose of the Dengue Virus Antibody Test
✔ Main Clinical Goals
- Diagnose acute dengue infection (IgM)
- Determine past infection or secondary infection (IgG)
- Support diagnosis alongside NS1 antigen test
- Evaluate febrile travelers returning from Southeast Asia or South America
✔ Common Indications
- Recent visit to endemic area
- Fever + rash + thrombocytopenia
- Exposure to Aedes mosquitoes
- Evaluation of acute undifferentiated viral fever
3. Test Method: ELISA (Enzyme-Linked Immunosorbent Assay)
Dengue Virus IgM/IgG testing is performed primarily using ELISA-based serology.
✔ Principle
- DENV antigen-coated wells
- Patient serum applied
- IgM or IgG antibodies bind if present
- Enzyme-tagged secondary antibody reacts
- Color change measured as optical density (OD)
- OD value → positive/negative according to kit-specific cut-off
✔ Antibody Characteristics
🔹 Dengue IgM
- Appears 4–5 days after symptom onset
- Peaks at 2 weeks
- Persists 2–3 months
- Best marker for acute primary dengue
🔹 Dengue IgG
- Rises within several days to weeks
- Persists for years or lifelong
- Indicates:
- Past infection
- Secondary infection (rapid high IgG rise)
- High IgG + IgM positivity → suggestive of secondary dengue, associated with severe disease risk
4. Interpretation of Dengue IgM/IgG Results
| IgM | IgG | Interpretation |
|---|---|---|
| + | – | Acute primary infection |
| + | + | Recent infection OR secondary infection |
| – | + | Past infection (or vaccination in endemic regions) |
| – | – | Early infection (≤3 days) OR no dengue → perform NS1 Antigen |
✔ Key Interpretation Notes
- High IgG + positive IgM → strong suspicion of secondary infection, higher DHF/DSS risk
- Early infection (day 1–3): IgM/IgG may be negative, NS1 antigen is more sensitive
- IgM wanes over months → not reliable for past infection
5. Clinical Significance
1) Acute Dengue Diagnosis
- IgM is essential for diagnosing acute primary infection.
- NS1 + IgM combo improves sensitivity and specificity significantly.
2) Secondary Infection Assessment
- Secondary dengue shows:
- Low or absent IgM
- Very high IgG (anamnestic response)
- Strongly associated with DHF/DSS due to ADE.
3) Staging the Infection
- IgM/IgG pattern helps estimate timing of infection
- Useful in managing patients in the critical phase (day 4–6)
4) Differential Diagnosis
Used to differentiate dengue from:
- Zika
- Chikungunya
- Yellow fever
- Other flavivirus infections
However, cross-reactivity is common → clinical correlation required.
6. Important Precautions in Interpretation
⚠ 1) Cross-reactivity among flaviviruses
- Zika, Yellow fever, Japanese encephalitis viruses may cause false-positive IgM/IgG
- Vaccination history and travel history must be reviewed
⚠ 2) Early-phase false negatives
- Antibodies may not appear until day 4–5
- NS1 antigen recommended for early detection
⚠ 3) Secondary infection patterns
- IgM may be weak or negative
- IgG shows rapid boosting
- Requires careful interpretation
⚠ 4) ELISA kit variability
- Cut-off OD values differ by manufacturer
- Follow laboratory-specific reference guidelines
⚠ 5) Immunocompromised patients
- Delayed or absent antibody response
- Combine with PCR or NS1 antigen testing
7. Quick Summary
| Category | Key Points |
|---|---|
| Test Purpose | Acute vs. past dengue infection, secondary infection evaluation |
| IgM | Appears day 4–5 → lasts 2–3 months |
| IgG | Rises later → persists for years |
| Most important pattern | High IgG + IgM(+) = secondary infection, severe disease risk |
| Cautions | Cross-reactivity, early false negatives, kit variability |
📚 References
- WHO. Dengue: Guidelines for Diagnosis, Treatment, Prevention and Control.
- CDC. Dengue: Clinical and Laboratory Guidance.
- Peeling RW et al. Evaluation of diagnostic tests for dengue. Nat Rev Microbiol. 2010.
- Guzman MG, Harris E. Dengue. Lancet. 2015;385(9966):453–465.
- Wilder-Smith A et al. Dengue. Lancet. 2019.