Diagnosis of acute hepatitis E: Which laboratory test is the most reliable for detecting recent HEV infection?

Introduction:
Hepatitis E typically presents as an acute, self-limited hepatitis with fecal–oral transmission. Accurate laboratory diagnosis focuses on detecting markers of recent infection, especially in outbreak settings and in pregnant patients where disease can be severe.

Given Data / Assumptions:

• The aim is to detect recent or ongoing HEV infection.
• Available assays include serology (IgM, IgG) and nucleic acid testing (PCR).
• We consider reliability and practicality for routine diagnosis.

Concept / Approach:
IgM anti-HEV appears during acute infection and is widely used for diagnosis via ELISA. PCR for HEV RNA is highly specific and useful, especially early or in immunocompromised hosts, but may be less accessible and time dependent due to transient viremia and assay availability. Many clinical algorithms consider IgM ELISA the most reliable front-line test for acute HEV in routine practice.

Step-by-Step Solution:
Define the clinical target: recent infection. Match serologic marker: IgM positivity indicates acute phase. Select ELISA for IgM anti-HEV as the standard, reliable, and widely used test.

Verification / Alternative check:
Public health guidance and common lab workflows endorse IgM ELISA as first-line in outbreaks; PCR complements serology when necessary.

Why Other Options Are Wrong:

• Western blot IgM: Confirmatory, not routine front-line, and less widely available.
• PCR HEV RNA: Very specific but limited by availability and timing; not always the chosen routine single best answer.
• ELISA IgG: Indicates past exposure rather than recent infection.
• Rapid antigen: Not standard for definitive acute HEV diagnosis.

Common Pitfalls:
Assuming PCR always equals most reliable; in many settings, validated IgM ELISA provides the best combination of sensitivity, specificity, and feasibility.

Final Answer:
ELISA for IgM anti-HEV is the most reliable routine test for acute HEV.