In November 1988, the Food and Drug Administration (FDA) recommended that all blood donation centers screen blood supplies for HTLV-I antibodies. This is to prevent the transmission of HTLV-I infection to recipients of blood components. In August 15, 1997 FDA issued a Guidance for Industry, Donor Screening for Antibodies to HTLV-II for all donations of Whole Blood and blood components intended for use in transfusion and Source Leukocytes.
A study of 39,898 random blood donors in eight US cities showed that 10 (0.025%) were found to have antibodies against HTLV-I (Willams et al., 1988). This established the fact that HTLV-I infection might be transmitted to recipients via transfusion of cellular blood products from infected donors (Okochi et al, 1984). Since the recommendation by FDA, approximately 2,000 HTLV-I/II-infected blood donors were identified during the first year of screening in the United States. Further confirmatory test such as PCR were performed to differentiate between HTLV-I and HTLV-II infections. The results showed up to be approximately 50% with HTLV-I infections and 50% with HTLV-II infections. These donors were subsequently counseled and permanently deferred from donating blood.