A patient who received a blood transfusion before age 12 now presents with chronic hepatitis symptoms and has positive hepatitis B surface antibody; which hepatitis virus is most likely causing his chronic hepatitis?

Hepatitis C is the Most Likely Cause of Chronic Hepatitis in This Patient

In a patient who received blood transfusions before age 12 and now presents with chronic hepatitis symptoms, hepatitis C virus (HCV) is the most likely causative agent, despite the presence of hepatitis B antibodies which indicate past exposure or vaccination rather than active chronic infection.

Understanding the Serologic Profile

The key to this case is recognizing that "HBV antibodies positive" most likely refers to anti-HBs (hepatitis B surface antibody), which indicates:

• Resolved past HBV infection or vaccination-induced immunity, not active chronic hepatitis B infection 1
• Anti-HBs positivity with negative HBsAg confirms viral clearance and immunity 1
• Chronic HBV infection requires persistent HBsAg positivity for >6 months, which is absent in this patient based on the description of "antibodies" rather than "antigen" 2

Why Hepatitis C is the Answer

Historical Transfusion Risk

• Blood transfusions before 1992 carried extremely high risk of HCV transmission because screening was unavailable 3
• Post-transfusion hepatitis C was the most common cause of transfusion-transmitted viral hepatitis in the pre-screening era 3
• 77% of patients with post-transfusion hepatitis developed chronic disease, with 32% progressing to cirrhosis after mean follow-up of 7.5 years 3

Natural History Favoring Chronicity

• HCV infection has a very high rate of progression to chronic infection - most infected individuals remain carriers with varying degrees of hepatocyte damage 4
• Only 10% of HCV-infected patients report acute illness, making subclinical infection the rule 3
• Chronic hepatitis C is the most common form of hepatitis infection worldwide in transfusion recipients from the pre-screening era 3

Thalassemia Population Data (If Applicable)

• Among transfusion-dependent patients (such as thalassemia), HCV antibody prevalence ranges from 4.4% to 85.4%, with genotype 1b being most common 3
• The incidence of chronic hepatitis C was dramatically higher among patients transfused before 1992 3

Why NOT Hepatitis B

• Chronic HBV infection requires HBsAg positivity, not antibody positivity 3, 2
• The presence of HBV antibodies (anti-HBs) indicates immunity and viral clearance, not active chronic infection 1
• Only 6-10% of adults infected with HBV develop chronic infection, compared to the much higher chronicity rate of HCV 3
• If this patient had chronic HBV, they would be HBsAg-positive, not antibody-positive 3, 2

Critical Diagnostic Algorithm

To confirm the diagnosis in this patient:

1. Test for anti-HCV antibodies - this will be positive in chronic HCV infection 3
2. Confirm with HCV RNA by PCR - detectable HCV RNA confirms active chronic infection 3
3. Verify HBsAg is negative - this confirms the "HBV antibodies" represent immunity, not active infection 1, 2
4. Check ALT/AST levels - typically elevated in chronic active hepatitis C 3
5. Determine HCV genotype - genotype 1b is most common in transfusion-associated cases and affects treatment decisions 3

Important Clinical Pitfalls

• Do not confuse HBV antibodies (anti-HBs) with HBV antigen (HBsAg) - only the latter indicates active infection 1, 2
• Patients can have serologic evidence of past HBV exposure (antibodies) while having active chronic HCV infection 3
• Co-infection with both HBV and HCV increases cirrhosis and HCC risk, but requires active replication of both viruses 3
• The patient's transfusion history before age 12 places them in the highest-risk cohort for transfusion-transmitted HCV 3

Long-Term Prognosis and Monitoring

• Persistent post-transfusion HCV infection leads to progressive liver disease in a significant proportion of patients 3
• After 20+ years post-transfusion, 51% had cirrhosis and 5.3% had hepatocellular carcinoma in one cohort 3
• The median time from HCV infection to cirrhosis is approximately 30 years 3
• Combination therapy with interferon and ribavirin can achieve sustained virological response in approximately 40% of chronic HCV patients, with rates dependent on genotype 5