Hepatitis C is the Most Common Virus Transmitted by Blood Transfusion
Hepatitis C virus (HCV) is the most common virus transmitted through blood transfusion, particularly in historical contexts. 1
Historical Context of Transfusion-Transmitted Viruses
Hepatitis C has been the predominant viral infection transmitted through blood transfusions, especially before modern screening methods were implemented:
- HCV was identified as the primary cause of what was previously called "non-A, non-B hepatitis" which accounted for 15-20% of community-acquired viral hepatitis in the United States 1
- During the 1980s, an estimated 230,000 new HCV infections occurred annually in the US, with transfusion being a major route of transmission 1
- Historical data showed that 90% of post-transfusion hepatitis cases were not caused by hepatitis A or B viruses but were primarily due to HCV 1
Evolution of Transfusion Risk
The risk of acquiring viral infections through blood transfusions has dramatically decreased over time:
- Before 1990, blood transfusion accounted for a substantial proportion of HCV infections 1
- Introduction of donor screening for HCV in May 1990 and more sensitive multi-antigen testing in July 1992 reduced the risk to approximately 0.001% per unit transfused 1
- Since 1994, the risk of transfusion-transmitted HCV has been so low that surveillance systems have been unable to detect transfusion-associated cases of acute hepatitis C, though the risk is not zero 1
Comparative Risk Among Blood-Borne Viruses
When comparing the major blood-borne viruses:
- HCV has historically been the most common virus transmitted by blood transfusion 1, 2
- During the 1996-1998 period, the residual risk for different viruses per donation was approximately:
- HCV: 1 out of 375,000 donations
- HBV: 1 out of 220,000 donations
- HIV: 1 out of 1,350,000 donations 2
Current Risk Status
Modern blood screening has dramatically reduced but not completely eliminated the risk of viral transmission:
- Current risk of transfusion-transmitted viral infection is estimated to be less than 2.5 per 1 million donations in the United States, Canada, and several European countries 1
- Nucleic acid technology (NAT) testing has further reduced the risk of transmission 2
- Despite these advances, HCV remains a significant concern for multitransfused patients such as those with thalassemia 3
High-Risk Populations
Patients requiring multiple transfusions remain at higher cumulative risk:
- A study of thalassemia patients found 25% were HCV positive by ELISA, with 65% of those having detectable HCV RNA 3
- Before effective screening was implemented, persons with hemophilia who received clotting factor concentrates had HCV infection rates as high as 90% 1
Prevention Strategies
The dramatic reduction in transfusion-transmitted HCV has been achieved through:
- Screening of blood donors for HCV antibodies and RNA
- Implementation of nucleic acid testing (NAT)
- Leukodepletion, which may reduce transmission of leukotropic viruses
- Viral inactivation procedures for plasma-derived products 2
It's important to note that while modern screening has dramatically reduced the risk of transfusion-transmitted HCV, it historically has been and remains the most common virus transmitted through blood transfusion when considering the entire history of transfusion medicine.