Emerging infectious disease issues in blood safety

Improvements in donor screening and testing and viral inactivation of plasm a derivatives together have resulted in substantial declines in transfusion -transmitted infections over the last two decades. Most recently, nucleic a cid testing techniques have been developed to screen blood and plasma donat ions for evidence of very recent viral infections that could be missed by c onventional serologic tests. Nonetheless, the blood supply remains vulnerab le to new and reemerging infections. In recent years, numerous infectious a gents found worldwide have been identified as potential threats to the bloo d supply. Several newly discovered hepatitis viruses and agents of transmis sible spongiform encephalopathies present unique challenges in assessing po ssible risks they may pose to the safety of blood and plasma products.