The RPR (Rapid Plasma Reagin) and VDRL (Venereal Disease Research Laboratory) tests are non-treponemal screening assays widely used to screen for syphilis in blood donors due to their high sensitivity, rapid results, and cost-effectiveness. These tests detect antibodies against cardiolipin-lecithin-cholesterol antigen released during cellular damage, making them suitable for initial broad screening. Positive results are typically confirmed with treponemal-specific tests like TPHA or FTA-ABS. ELISA, TPHA, and FTA-ABS are more specific but are used primarily for confirmation rather than mass screening. Thus, RPR/VDRL remains the standard first-line screening test in blood donation settings.

Reference: Harrison's Principles of Internal Medicine, Jameson et al., 20th Edition.