Prevention of transmission of human T‐lymphotropic virus type 1 (HTLV‐1) through transfusion, by donor screening with antibody to the virus One‐year experience

Abstract

To prevent the transmission of human T-lymphotropic virus, type 1 (HTLV-1) during blood transfusion, a program was implemented to screen donors for antibodies to the virus, using a newly developed, passive agglutination (PA) method. During the period April 1986 to March 1987, 675 recipients of donor blood in whom the antibody to HTLV-1 was not present before transfusion were followed for at least 50 days after transfusion. One of these 675 seroconverted despite the transfusion of screened blood, but this seroconversion rate (0.15%) represents a marked decrease from the rate of 8.3 percent prevalent before donor screening began. The rate in the Fukuoka area of donors seropositive for anti-HTLV-1 is 5.34 percent, as detected by the PA method and 1.80 percent, as assessed by the indirect immunofluorescence (IF) technique, with PA-positive but IF-negative blood units thus accounting for 3.5 percent (5.34-1.80) of the total blood donated. The seroconversion rate among recipients transfused with blood screened by IF (at Kyhushu University Hospital only) for 1981 to 1985 was 0.41 percent, which was not significantly different from the rate of 0.15 percent observed after PA screening. The discrepancy between PA and IF in the rate of seropositivity was due, in part, to the higher sensitivity of PA in detecting anti-HTLV-1. It is proposed that all donor blood in areas where HTLV-1 is endemic be screened by PA before transfusion. For reasons of expense and equipment unavailability, it is not possible for IF to be used n a general basis, but because of the possibility of false-positive results with PA, PA-positive blood units should be reexamined by IF or Western blot testing to reduce the amount of wasted blood, especially in areas highly endemic for HTLV-1, such as Kyushu, Japan.