Abstract

PIP: According to reports presented at a July 1985 US Public Health Service workshop on human T-lymphotropic virus type III (HTLV-III) antibody testing, enzyme immunoassay serologic tests in current use at blood banks, plasma collection centers, health departments, and other clinical settings are both highly sensitive and specific. HTLV-III antibody test data have been accumulated from over 1.1 million units of blood collected at 155 centers, 2831 (0.25%) of which were positive after repeated testing. The Atlanta Region of the American Red Cross and the Centers for Disease Control reported data from testing over 51,000 donors, 0.23% of whom were repeatedly reactive by the Abbott enzyme immunoassay test. 32% of repeatedly reactive tests were strongly reactive. Of 220 donors whose tests were initially reactive and subsequently negative, none had either a positive Western blot test or positive culture for HTLV-III virus. To determine the sensitivity of the Abbott test in high-risk persons, virus isolations were attempted from homosexual men in San Francisco. None of 70 men with negative HTLV-III antibody tests had a positive culture, while 43 (60%) of 72 men with repeatedly reactive tests were culture-positive. 97% of positive tests in this population were highly reactive. Weakly reactive enzyme immunoassay tests tend to correlate poorly with positive Western blot tests and are generally nonspecific for HTLV-III infection. Screening is judged to have so far removed as many as 1000 potentially infectious units of blood from the US blood supply.