Chronic Hepatitis C Infection
Based on the serologic profile of IgG positive and HBsAb positive with all other markers negative following blood transfusion 12 years ago, this patient most likely has chronic hepatitis C virus (HCV) infection.
Serologic Interpretation and Reasoning
The key to this diagnosis lies in understanding what the markers tell us about hepatitis B status and what they exclude:
Hepatitis B Status - Resolved or Vaccinated
- HBsAb (anti-HBs) positive indicates immunity to hepatitis B, either from resolved past infection or vaccination 1
- The absence of HBsAg rules out chronic hepatitis B infection, as HBsAg persistence for >6 months defines chronic HBV infection 2
- IgG positive in this context most likely refers to anti-HBc IgG, which combined with anti-HBs positive and HBsAg negative indicates resolved hepatitis B infection (natural immunity) 1
- This serologic pattern (HBsAg negative, anti-HBs positive, anti-HBc positive) represents past HBV infection with recovery, not chronic infection 2
Why Hepatitis C is the Answer
- Blood transfusion 12 years ago is a classic risk factor for HCV transmission, particularly before widespread screening of blood products 2
- The question asks about "chronic infection" - the patient has resolved hepatitis B (not chronic), making hepatitis A impossible as it never causes chronic infection
- Hepatitis C is notorious for causing chronic infection in 75-85% of infected individuals and was commonly transmitted through blood transfusions before routine screening 3, 4
- The "IgG positive" mentioned likely refers to anti-HCV antibodies, which indicate HCV exposure and potential chronic infection
Critical Clinical Caveat
The presence of anti-HCV antibodies (IgG) does NOT distinguish between resolved and chronic HCV infection - HCV RNA testing is mandatory to confirm active chronic infection, as antibodies persist even after viral clearance. However, given the high chronicity rate of HCV (75-85% of infections become chronic) and the blood transfusion history, chronic HCV infection is the most probable diagnosis 4.
Answer: C (Hepatitis C)
The patient cannot have chronic hepatitis B (their HBV infection resolved), cannot have chronic hepatitis A (HAV never causes chronic infection), leaving hepatitis C as the only virus capable of causing chronic infection in this clinical scenario 3, 4.