Transmission of infection

The transmission of infectious agents is a small but serious risk of blood transfusion. Possible agents include:

• hepatitis B and C - blood donations are now screened for these agents. The surface antigen, HBsAg, forms the basis of screening for hepatitis B virus and occasionally transmission may take place because a donor is in an early phase of infection before antigen is detectable
  
  
• CMV - may occur as the virus can remain dormant in leukocytes. Immunocompromised patients without anti-CMV antibodies, and neonates, should be given blood from CMV-negative donors only
  
  
• HIV-1 - donated blood is screened for anti-HIV antibodies but there remains a very small risk of transmission - estimated at 1 in 300,000 units transfused - since antibody may not yet have developed in the donor
  
  
• infectious mononucleosis may occasionally be transmitted
  
  
• syphilis transmission is rare as all donations are screened for treponemal infections and the infectivity of Treponema pallidum declines as blood is stored at 2 - 6 degrees C
  
  
• malaria - rare in the UK as the method of donor selection is designed to exclude potentially infectious donors. It is more likely in endemic areas in which anti-malarial drugs are advised for blood recipients
  
  
• other rare potential contaminants include brucella, plasmodia, trypanosomes