What is the most common virus transmitted by blood transfusion (Blood Transfusion)?

Hepatitis C is the Most Common Virus Transmitted by Blood Transfusion

Hepatitis C virus (HCV) is the most common virus transmitted through blood transfusion, accounting for the majority of transfusion-associated viral hepatitis cases historically. 1

Historical Context and Epidemiology

Historically, HCV has been the predominant viral infection transmitted through blood transfusions:

• Before 1990, HCV (then known as non-A, non-B hepatitis) accounted for approximately 90% of all post-transfusion hepatitis cases in the United States 1
• In the 1970s, the incidence of post-transfusion non-A, non-B hepatitis (later identified as primarily HCV) was as high as 21% 1
• By the late 1970s, this had decreased to approximately 10% among transfusion recipients 1

Risk Reduction Over Time

The risk of acquiring HCV through blood transfusion has dramatically decreased due to several interventions:

• Introduction of donor screening policies in the 1980s reduced transfusion-associated hepatitis by more than 50% 1
• Implementation of anti-HCV testing in 1990 further reduced transmission risk 1
• By 1992, more sensitive multi-antigen testing was implemented, reducing the risk to approximately 0.001% per unit transfused 1
• Current risk of transfusion-transmitted viral infection (including HCV) is estimated to be less than 2.5 per 1 million donations in developed countries 1

Comparison with Other Transfusion-Transmitted Viruses

When comparing the major transfusion-transmitted viruses:

1. Hepatitis C (HCV):

   • Historically the most common transfusion-transmitted virus 1
   • Accounted for 90% of post-transfusion hepatitis before specific testing 1

2. Hepatitis B (HBV):

   • Current incidence of post-transfusion hepatitis B is estimated to be around 0.002% per transfusion recipient 1
   • Risk has been significantly reduced through HBsAg screening (mandatory since 1972) and anti-HBc testing 1

3. HIV:

   • Transmission risk has been drastically reduced through antibody screening 2
   • Less common than hepatitis viruses historically in transfusion transmission

Current Status

While modern blood screening has dramatically reduced the risk of all transfusion-transmitted infections, HCV remains significant because:

• It was historically the most prevalent virus in the blood supply
• It has a high rate of progression to chronic infection (75-85% of infected individuals)
• It leads to significant morbidity and mortality through chronic liver disease 1

Clinical Implications

The clinical significance of HCV as the most common transfusion-transmitted virus is substantial:

• Chronic HCV infection is responsible for approximately 40% of chronic liver disease in the United States 1
• It results in an estimated 8,000-10,000 deaths annually 1
• Medical and work-loss costs related to HCV-associated liver disease exceed $600 million annually 1

Prevention Strategies

Modern prevention strategies have virtually eliminated transfusion-transmitted HCV in developed countries through:

• Nucleic acid testing (NAT) to detect viral RNA during the window period 3, 4
• Stringent donor selection criteria 1
• Pathogen inactivation technologies for blood products 4

Despite these advances, HCV remains historically the most common virus transmitted through blood transfusion, with significant public health implications for those infected before modern screening methods were implemented.