This is a prospective study designed to assess the safety and effectiveness of a dual algorithm testing for HTLV I/II in blood donors. The study hypothesis is that blood donors testing repeat reactive (RR) on the first FDA licensed HTLV screening assay and non-reactive (NR) on a second FDA licensed screening assay will be confirmed as indeterminate or negative on the MP Diagnostics HTLV Blot 2.4.