Hepatitis E (HEV) Test
🦠 Hepatitis E (HEV) Testing: Complete Guide to IgM, IgG, and HEV RNA
1. What Is Hepatitis E (HEV)?
Hepatitis E is an acute viral hepatitis caused by the Hepatitis E Virus (HEV). It is one of the leading causes of acute viral hepatitis worldwide.
Key Features
- Most common transmission: contaminated water or food (fecal–oral route)
- Typical in travelers returning from endemic regions
- Usually self-limited in healthy adults
- High mortality in pregnancy, especially 3rd trimester (notably genotype 1)
- Chronic HEV may occur in immunocompromised individuals (genotype 3)
- Requires prompt serologic diagnosis in high-risk groups
2. Purpose of HEV Testing
| Test | Purpose |
|---|---|
| Anti-HEV IgM | Detects acute or recent HEV infection |
| Anti-HEV IgG | Detects past infection or immunity |
| HEV RNA (PCR) | Detects active viral replication; critical in chronic/immunocompromised patients |
Routine evaluation typically begins with IgM/IgG ELISA.
3. Test Method — ELISA
ELISA (Enzyme-Linked Immunosorbent Assay) is the primary method for HEV antibody testing.
How ELISA Works
- HEV antigens are immobilized on a plate
- Patient antibodies (IgM or IgG) bind if present
- Enzyme-linked antibodies create a measurable color change
- Signal intensity corresponds to antibody level
Specimen
- Serum
- Fasting not required
Advantages
- High sensitivity and specificity
- Standardized across international labs
- Suitable for high-throughput testing
4. Reference Ranges (Typical Values)
(Manufacturer-specific values may vary)
Anti-HEV IgM
- Negative → No acute/recent infection
- Positive → Acute or recent HEV infection
Anti-HEV IgG
- Negative → No past infection / no immunity
- Positive → Past infection or long-term immunity
5. Clinical Significance of HEV Tests
1) Anti-HEV IgM Positive
- Most important marker of acute hepatitis E
- Appears early in infection, remains detectable for 3–4 weeks
- Strongly associated with elevated ALT/AST
2) Anti-HEV IgG Positive
- Indicates past infection or immunity
- If IgM is negative → Represents recovery or remote infection
3) HEV RNA (PCR)
- Detects active viral replication
- Essential for:
- Immunocompromised patients (transplant, HIV, chemotherapy)
- Suspected chronic HEV
- Severe hepatitis with unclear diagnosis
6. Typical Serology Patterns
| Clinical Stage | IgM | IgG |
|---|---|---|
| Early acute infection | + | − / + |
| Recovery phase | − | + |
| Past infection | − | + |
| No immunity | − | − |
IgM (+) with IgG (+) is common during the recovery or late acute phase.
7. Important Considerations When Interpreting HEV Tests
⚠️ 1) IgM false positives
Possible in:
- Other viral infections
- Autoimmune hepatitis
- High Rheumatoid Factor (RF)
→ Always interpret with symptoms + liver enzymes.
⚠️ 2) Immunocompromised patients
- IgM may be weak or absent
- HEV RNA is more reliable
- Chronic infection more common (genotype 3)
⚠️ 3) Pregnancy
- Particularly severe, especially in 3rd trimester
- Risk of:
- Fulminant liver failure
- Maternal mortality
- Adverse fetal outcomes
Any pregnant woman with IgM positivity requires immediate specialist care.
⚠️ 4) Travel and dietary exposure
Important clues:
- Recent travel to South Asia, Africa, Middle East
- Consumption of:
- Undercooked pork
- Wild boar, deer meat (genotype 3)
8. Summary
| Item | Key Point |
|---|---|
| Test Method | ELISA |
| IgM | Acute or recent infection |
| IgG | Past infection or immunity |
| Specimen | Serum |
| Key Interpretation | IgM(+) → Acute / IgG(+) → Past or recovery |
| Special Risks | Pregnancy, immunosuppression |
9. References
- Tietz Textbook of Clinical Chemistry and Molecular Diagnostics, 6th ed.
- Henry’s Clinical Diagnosis and Management by Laboratory Methods, 24th ed.
- WHO. Hepatitis E Fact Sheet.
- CDC. Viral Hepatitis – Hepatitis E Information.
- Kamar N, Dalton HR. Hepatitis E virus infection. Clin Microbiol Rev.