Hepatitis B Serology Interpretation

Explanation

Persistence of hepatitis B surface antigen defines ongoing infection, and persistence beyond 6 months, or its presence with core IgG rather than core IgM, defines chronic infection. Anti-core IgM is the marker of acute infection and of the window period, so its absence together with positive anti-core IgG places this patient well past the acute phase. The combination of e antigen negative, anti-e positive, normal transaminases and a viral load below 2,000 IU/mL corresponds to the e antigen-negative chronic infection phase, previously called the inactive carrier state, which carries a good prognosis but still requires 6 to 12 monthly monitoring of ALT and viral load because reactivation and e antigen-negative hepatitis can occur. Vaccine-derived immunity produces isolated anti-surface antibody with negative surface antigen and negative core antibody, since the vaccine contains only surface antigen. Resolved natural infection gives negative surface antigen with both anti-surface and anti-core antibodies positive. Here anti-surface antibody is negative and surface antigen is positive, which excludes both immune patterns. Chronic carriers need hepatocellular carcinoma surveillance with ultrasound every 6 months when risk factors such as cirrhosis, Asian male above 40 years or a family history are present, and household contacts should be screened and vaccinated. Antiviral treatment with tenofovir or entecavir is indicated when there is cirrhosis, a viral load above 2,000 IU/mL with raised ALT, or significant fibrosis on elastography.

Why each option

A.

Acute infection would show positive anti-core IgM with markedly raised transaminases; this patient has core IgG only and a normal ALT.

B.

Correct. Positive surface antigen with anti-core IgG, negative anti-surface antibody, e antigen negativity and a low viral load indicate chronic e antigen-negative hepatitis B infection.

C.

Vaccination produces isolated anti-surface antibody with negative surface antigen and negative core antibody, the opposite of this pattern.

D.

Resolved infection shows negative surface antigen with both anti-surface and anti-core antibodies positive, whereas this patient remains surface antigen positive.

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