Which infectious agent is least likely to be transmitted by a blood transfusion?

• A. HIV
• B. HBV
• C. HCV
• D. HAV

Answer: (D)

Transfusion safety hinges on how often a pathogen is present in the bloodstream of healthy-appearing donors. Pathogens that cause ongoing viremia and are common in the donor population pose a real risk for transmission through blood products, which is why HIV, hepatitis B, and hepatitis C are classic transfusion-transmitted infections and are specifically screened for.

Hepatitis A virus, on the other hand, is mainly spread through the fecal-oral route and typically causes an acute illness. Its viremia is brief and not a routine feature of the infection in a way that would routinely put blood donors at risk. Because of this pattern, HAV is much less likely to be transmitted by a blood transfusion compared with HIV, HBV, or HCV, making it the least likely among the choices. Rare transfusion-transmitted HAV cases have been reported, but they are exceedingly uncommon relative to the other viruses.