Question

Which of the following is a marker for recent (acute) hepatitis B infection?

• A. IgM anti-HBs
• B. IgM anti-HBc
• C. HBeAg
• D. HBsAg

Hint:

IgM anti-HBc is positive early and is the only marker seen during the window period of acute hepatitis B.

Answer 1

The Correct Option is B

Step 1: Understanding the Question:
Hepatitis B has several serological markers that appear at different times during infection, and the question asks which one specifically tells us the infection is recent, meaning acute.

Step 2: Key Concept:
HBsAg and HBeAg can be present in both acute and chronic infection, so on their own they cannot separate a brand new infection from a long standing one. Anti-HBc, the antibody against the core antigen, appears early and its IgM form is short lived, which makes IgM anti-HBc a marker of a recent infection, not an old or chronic one.

Step 3: Detailed Explanation:
IgM anti-HBc rises within weeks of infection and typically stays positive for about six months, exactly the window we call acute hepatitis B. It is also the only positive marker during the so called window period, when HBsAg has already cleared and anti-HBs has not yet appeared, so it is the single most reliable marker of recent infection.
HBsAg shows that the virus is present, but it stays positive in chronic carriers for years, so a positive HBsAg alone does not tell us whether the infection is new.
HBeAg reflects active viral replication and high infectivity, and it can be positive in both acute and chronic active hepatitis B, so it does not specifically mark recency either.
IgM anti-HBs is not the marker used clinically, since anti-HBs (mostly IgG) appears late, after recovery, and signals immunity or past vaccination rather than a recent infection.

Step 4: Final Answer:
IgM anti-HBc is the marker that specifically identifies a recent, acute hepatitis B infection.