Most infectious agents transmissible by transfusion have been around for many years, so in general it is prior donor activity that determines whether a unit of blood is infected or not. Occasionally a new microbe, like the human immunodeficiency virus (HIV) or Babesia mnicmti, is introduced. And, while West Nile Virus may have been in Africa for some time, it was first identified only recently in the United States. Regardless whether it is an ancient or new agent, similar human activities are likely to underpin their entry into and transmission along the medical blood supply. They include intravenous drug use with needle-sharing, high-risk or multiple partner sexual activity, exposure to insect vectors, travel, population migration, and medical negligence, and each may be influenced by economic, political, and social conditions. These subjects are discussed elsewhere in this volume, so this chapter will focus on their specific impact on blood safety.
By far the greatest challenge to blood safety today is in the developing world, primarily in sub Saharan Africa and parts of Asia, as a consequence of inadequate resources and dated technology in the health sector. The result has been epidemics of transfusion-related HIV, hepatitis, and other infectious diseases. Failing to test all donated blood for infectious agents is thought to have caused up to 16 million HBV infections, 5 million HCV infections, and 160,000 cases of HIV worldwide (Heyns et al., 2005). In 1975, a World Health Assembly (WHA) resolution called for countries to adopt nationally coordinated, voluntary blood transfusion services. So far, fewer than 30 percent of the signatory states have done so. In contrast, developed nations have made a deliberate policy to ignore cost in order to emphasize safety. The result has been steady increases in transfusion safety and cost. In the United States, the Food and Drug Administration (USFDA) has been regulating blood-banking for several decades. However, around 1990 the FDA also started applying the regulations for pharmaceutical manufacture to blood-banking. Also, in its mission to protect the public health, it is not permitted to consider cost when promulgating rules and conducting oversight - so, even though proven not to be cost-effective, the FDA approved, on an interim basis, p-24 antigen testing for HIV The FDA at the time was looking ahead to when a more effective NAT test would be available. Still, one study estimated it costs about $2 million to prevent one case of transfusion-related HIV (Heyns et al., 2005). Currently, NAT is routinely performed to detect HIV-1, hepatitis C Virus (HCV), and West Nile virus. Figure 7.1 illustrates the steady rise in the price of blood-banking services, due in part to increased testing. It should also be noted that in earlier years blood centers traditionally had underpriced the cost of providing red cells for transfusion.
The challenge is to make widespread testing commonplace in countries where cost is a limiting factor. Currently, advanced testing for HIV and HCV, and bacterial culture tests on platelets, are not available in most developing countries.
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