Human T‐lymphotropic virus antibody screening of blood donors: rates of false‐positive results and evaluation of a potential donor reentry algorithm

Abstract

Donors testing falsely positive by historic EIAs since 1988 should be considered for reinstatement if a contemporary sample tests ChLIA nonreactive. Changes to the existing screening algorithm seem unlikely since new HTLV infections were detected among repeat donors.

HTLV-1 in Solid-Organ Transplantation

“…Those blood samples that are positive twice on ELISA testing are referred to as ''repeat reactive''. ELISAs are sensitive (~100%) but lack specificity in populations of low HTLV prevalence (such as the United States and Europe) (30,31). Confirmatory testing should be performed with immunoblotting (i.e., Western blotting or specific line immunoassay), which, unlike ELISAs, can differentiate between HTLV-1 and HTLV-2 infection by identification of specific viral protein products (4).…”

Discordant human T‐lymphotropic virus screening with Western blot confirmation: evaluation of the dual‐test algorithm for US blood donations

“…Screening for human T‐lymphotropic virus (HTLV) antibodies in the United States was mandated by the Food and Drug Administration (FDA) in 1988 (first for HTLV‐1 followed by HTLV‐2 in 1998) . In the United States, HTLV prevalence is relatively low at 3.37 per 100,000 donations collected from 2011 to 2012 .…”

“…Before the availability of a licensed supplemental assay, repeat‐reactive (RR) samples on a first assay (Assay 1) were retested with a second screening assay (Assay 2). Donors with RR results by Assay 2 were deferred from blood donation and further tested using an unlicensed supplemental test to confirm reactivity while nonreactive (NR) donors remained eligible for donation until RR on a subsequent donation . This “dual‐test” algorithm was replaced in May 2016 with the FDA requirement (Federal Register 29842; May 22, 2015) that all RRs by Assay 1 be further tested by a licensed HTLV supplemental test (Western blot [WB]).…”

A retrospective analysis of false‐positive infectious screening results in blood donors

“…Unlike false‐negative test results, false‐positive results do not pose an immediate risk to recipient health; however, they are still problematic. From 1995 to mid‐2008, approximately 64,000 allogeneic donors at the American Red Cross (ARC) were deferred based on HTLV false‐positive enzyme immunoassay results, representing 130,000 US donors . Similarly, among first‐time ARC donors who donated whole blood between 1995 and 2002, approximately 13,000, 57,000, and 20,000 donors were deferred for unconfirmed reactive results on HBV, HCV, or HIV, respectively .…”