Hepatitis C is the Most Common Virus Transmitted by Blood Transfusion
The correct answer is C. Hepatitis C virus (HCV) is the most common virus transmitted by blood transfusion.
Epidemiology and Historical Context
Historically, HCV has been the predominant virus transmitted through blood transfusions in the United States and globally. Before effective screening methods were implemented, HCV accounted for the majority of post-transfusion hepatitis cases 1:
- In the 1960s, post-transfusion hepatitis rates exceeded 20%
- By the mid-1970s, 90% of post-transfusion hepatitis was identified as non-A, non-B hepatitis
- Later research confirmed that non-A, non-B hepatitis was primarily caused by HCV infection
Prior to effective screening, blood transfusion accounted for a substantial proportion of HCV infections, and HCV consistently represented the highest risk of viral transmission through transfusion 1.
Comparison with Other Hepatitis Viruses
Hepatitis A
- Not typically transmitted through blood transfusions
- Primarily spreads through fecal-oral route
- Not included in blood donor screening protocols
Hepatitis B (HBV)
- Screening for HBV began in 1969 and became mandatory in 1972
- Introduction of HBsAg testing dramatically reduced transmission
- Current risk of HBV transmission is approximately 0.002% per transfusion recipient 1
- Significantly lower transmission rate than HCV historically
Hepatitis C (HCV)
- Historically accounted for 90% of post-transfusion hepatitis cases
- Was the predominant risk until effective screening was implemented
- Even after implementation of donor screening in 1990, remained the most significant transfusion-transmitted viral infection 1
CMV (Cytomegalovirus)
- While CMV can be transmitted through transfusion
- Not routinely screened for in all blood products
- Primarily a concern for immunocompromised recipients
- Not historically the most common transfusion-transmitted virus
Current Risk Status
Modern blood screening has dramatically reduced the risk of all transfusion-transmitted viral infections:
- Since 1994, the risk of transfusion-transmitted HCV infection has been extremely low (0.001% per unit transfused) 1
- Current risks for HBV and HCV are approximately 1 in 63,000 and 1 in 125,000 per unit, respectively 2
- Despite these improvements, HCV historically represented the greatest viral risk in blood transfusion
Special Considerations
- Occult HBV infection (OBI) remains a concern but occurs at a much lower rate than historical HCV transmission
- The prevalence of OBI in blood donors was estimated to be only 8.55 per 1 million donations 3
- The risk of viral transmission through transfusion is now so low that background rates of viral hepatitis greatly exceed the risk of transmission via transfusion 2
Despite modern screening methods making all transfusion-transmitted viral infections rare, historically and in terms of overall impact on public health, HCV has been the most common virus transmitted through blood transfusion.