A 33-year-old man has never been vaccinated for hepatitis B. Serologic tests reveal negative hepatitis B surface antigen (HBsAg) and positive antibody to surface antigen. Which of the following conditions does this serologic pattern best fit with?: (A) previous hepatitis B infection, (B) chronic active hepatitis, (C) acute hepatitis B infection, (D) poor prognosis
Answer is A. The antibody can be demonstrated in 80-90% of patients, usually late in convalescence, and indicates relative or absolute immunity. In contrast, HBsAg occurs very early and disappears in < 6 months. Persistence of HBsAg indicates chronic infection. The pattern in this patient is also seen postvaccination, and perhaps as a consequence of remote infection.