An expanded "look-back" program has been developed, in which patients who may have been exposed to HIV through blood transfusion were identified via three triggers: the blood that they received was donated by persons who 1) have subsequently been reported to local health departments as meeting the diagnostic criteria for AIDS, 2) have donated since the introduction of anti-HIV screening and tested positive, or 3) have been found to be infected during investigation of reported transfusion-associated HIV infections. In comparing triggers, cross-referencing the list of patients reported to have AIDS (AIDS case list) proved to be the most efficient approach for identifying HIV-infected donors and transfusion recipients. Of the 7973 AIDS patients reported in eight Northern California counties as of December 1988, 316 (4.0%) were determined to have donated at Irwin Memorial Blood Centers between 1977 and 1985. Despite the logarithmic increase in reported cases of AIDS in the San Francisco Bay area over the last 5 years, the rate of detection of previous donors from AIDS case lists remained between 3.3 and 5.4 percent. These persons accounted for 69 percent of the identified infected donors, and their identification led to notification of 60 percent of potentially exposed recipients and 51 percent of known infected recipients. The crossreferencing of AIDS case listings with blood bank records was equally efficient for regions with low and high AIDS prevalence. National adoption of AIDS case list crossreferencing is recommended as an effective means of identifying previously unidentified infected recipients in an effort to limit the secondary spread of HIV infection.

Acquired Immunodeficiency Syndrome↗

PubMedDate not supplied

Increased detection of hepatitis C virus (HCV)-infected blood donors by a multiple-antigen HCV enzyme immunoassay.

A new, multiple-antigen enzyme immunoassay (EIA-2) for hepatitis C virus (HCV) antibodies was evaluated in parallel with the previously available c100-3 HCV EIA (EIA-1) in 14,068 volunteer blood donors as well as in 25 cases of transfusion-associated hepatitis C for which recipient and donor samples were available. When compared to EIA-1, the EIA-2 was more sensitive in detecting HCV-infected blood donors. The EIA-2 detected an additional 1 in 1000 EIA-1-negative, surrogate marker-negative donors who were infected with HCV as demonstrated by polymerase chain reaction (PCR). The specificity of the EIA-2 was comparable to that of the EIA-1, but the two tests appear to detect different populations of false-positive donors. Recombinant immunoblot assay-indeterminate donors were detected five times more frequently by the EIA-2; PCR demonstrated that 21 percent of these donors were infected with HCV. The greater sensitivity of EIA-2 was also found in 25 transfusion recipients with non-A, non-B hepatitis; however, in 16 percent of these cases of posttransfusion HCV infection, the EIA-2 failed to detect an HCV-seropositive donor. These data indicate that EIA-2 testing will significantly reduce, but probably not eliminate, the risk of transfusion-associated HCV infection; we estimate this residual per-unit risk to be 1 in 2000 to 1 in 6000 units transfused. On a national level, it is projected that the replacement of the anti-HCV EIA-1 with the EIA-2 will initially prevent up to 40 additional cases of transfusion-associated hepatitis C per day.

Blood Donors↗