The quest for a zero-risk blood supply
Over the past few years, the crows in much of the Eastern United States fell silent. Many of the birds were victims of the emerging pathogen called West Nile virus. Originally from Africa, the virus entered the United States only a few years ago and is now spreading across the country in migrating birds (SN: 12/11/99, p. 378: http://www.sciencenews.org/sn_arc99/12_11_99/bob1.htm). The disease typically jumps from birds to people via mosquitoes. In September 2002, however, scientists with the Centers for Disease Control and Prevention (CDC) in Atlanta reported that a few people had been infected with West Nile virus through blood transfusions. That worries officials who recall the tragedies of the late 1970s and early 1980s, when thousands of people contracted HIV from contaminated blood products and later developed AIDS.