BOX 2-4 How Safe Is the Blood Supply?
Many of the 4 million people who receive a blood transfusion in the United States each year have concerns about contracting a communicable disease in the process. Like organs and other tissues that are transplanted, blood is a biological product that can host disease-causing microorganisms. Fortunately, however, blood that is donated today goes through a battery of tests designed to ensure that it is free of contamination by infectious agents. The American Red Cross (ARC) now tests donor blood for syphilis, hepatitis B and C, human T-lymphotrophic virus types 1 and 2 (HTLV-I and HTLV-II), HIV-1, and, recently, HIV-2 as well. HIV-2 currently ranks as the primary cause of HIV disease only in West Africa; yet as of September 1991, 31 people in the United States had been diagnosed with HIV-2 infection, making the virus a potential threat to the safety of the blood supply in this country (Johnston, 1991).
The Department of Defense (DOD) and the American Association of Blood Banks (AABB) recently took steps to protect the blood supply from contamination with another microorganism, the leishmania parasite. Found primarily in Africa and Asia, the parasite was found late last year in the blood of more than two dozen soldiers returning from the Persian Gulf War. Both the DOD and the AABB, as well as the ARC, plan to refuse donations until at least 1993 from all individuals—mainly members of the U.S. armed services—who have traveled to the Middle East since August 1990.
Many of the efforts made by blood banks to improve the safety of the blood supply have been tremendously successful. Thirty years ago, nearly one in three people who received a blood transfusion contracted some form of hepatitis; today, that risk has dropped to less than 1 in 100 (Russell, 1991). The chances of contracting HIV from a blood transfusion are considerably less than in the early 1980s, when AIDS was first identified. Prior to 1985, when testing for HIV in donor blood became widespread, more than 4,300 persons were infected by the virus through blood transfusions. From 1985 through December 1991, only 20 people have acquired HIV through transfusions (Centers for Disease Control, 1992e). The risk of HIV infection from a blood transfusion has been estimated at from 1 in 40,000 to 1 in 150,000 per unit of blood transfused, depending on the region from which the blood originated (Russell, 1991).
Safeguards against microorganism-contaminated blood unfortunately are not foolproof. As a result, doctors have become much more conservative about using transfusions. Most encourage patients to contribute their own blood prior to surgery whenever possible, and many doctors have sought new alternatives to transfusions altogether. Automated cell salvage techniques that can be used either during or after surgery to recover, cleanse, and return lost blood are one such alternative. Until the search for an effective blood substitute is successful (several companies appear to be close to developing a safe product), protecting the blood supply and its users from infectious disease remains a top priority.