Beyond HIV, HBV and HCV--how to deal with other viruses?

Transmission of viruses such as HBV, HIV and HCV by blood components and protein fractions are well documented and precautions based on donor selection and screening as well as processing are well established and effective. Other viruses, including small non-enveloped viruses, pose a greater challenge for removal, but are considered less hazardous clinically. While cell associated viruses such as HTLVI and CMV pose a risk to certain kinds of recipient of blood components the biggest single current issue is that of vCJD following the BSE epidemic in the United Kingdom.