Hepatitis C is the Most Common Virus Transmitted by Blood Transfusion
The answer is C. Hepatitis C (HCV) is historically the most common virus transmitted by blood transfusion, accounting for the majority of post-transfusion hepatitis cases. 1
Historical Context and Epidemiology
Hepatitis C virus has been the predominant transfusion-transmitted viral infection, with:
- Historical transmission rates exceeding 20% in the 1960s 1
- Approximately 10% of transfusion recipients developed non-A, non-B hepatitis (later identified as primarily HCV) before implementation of donor screening 1
- Studies demonstrated that 90% of post-transfusion hepatitis was not caused by hepatitis A or B viruses 1
Comparison with Other Transfusion-Transmitted Viruses
While multiple viruses can be transmitted through blood transfusions, HCV has historically been the most significant:
- Hepatitis B (HBV): Transmission rates were reduced to 0.3%-0.9% per transfusion recipient by the mid-1970s due to improved screening 1
- HIV: While a serious concern, HIV has never been the most common transfusion-transmitted virus 2
- Hepatitis A: Not typically transmitted through blood transfusions (not mentioned as a significant transfusion risk in the guidelines)
- CMV: While transmissible through cellular components of blood, it has not been the most common transfusion-transmitted virus 3
Evolution of Blood Safety Measures
The risk of HCV transmission through blood transfusion has decreased dramatically over time due to:
- Shift from paid to volunteer blood donors 1
- Implementation of anti-HCV antibody screening 1
- Nucleic acid testing (NAT) for HCV 1
- Use of surrogate markers like ALT and anti-HBc testing 1
Current risk estimates for transfusion-transmitted viruses in the US have been reduced to between one and four per million blood components transfused 2, with specific risks for HCV estimated at 1 in 125,000 per unit 4.
Clinical Implications
For healthcare providers managing patients who have received blood transfusions:
- Patients with abnormal liver function tests after receiving blood products should be tested for HCV and other hepatitis viruses 1
- Despite advanced screening methods, zero risk has not yet been achieved 5
- Modern transfusion practice still carries some risk due to factors like prolonged viremia, inapparent infections, and carrier states 3
Pitfalls and Caveats
- False negatives still persist despite advanced testing methods 5
- The window period between infection and detectability remains a challenge even with NAT testing 6, 5
- Immunocompromised patients may be at higher risk for infection even with lower viral loads 6
- While HCV remains historically the most common transfusion-transmitted virus, current transmission rates for all viruses are extremely low due to improved screening methods