Efficacy of donor screening for HTLV-I and the natural history of transfusion-transmitted infection.

BACKGROUND

It has been 10 years since the implementation in Japan of donor blood screening for human T-cell lymphotropic virus type I (HTLV-I). This report reviews the effectiveness of screening in preventing transmission of HTLV-I through blood transfusion and the current status of patients with confirmed seroconversion due to transfusions given before the implementation of screening.

STUDY DESIGN AND

METHODS

Patients who received blood at Kyushu University Hospital from 1990 to 1997 were followed. Serum samples were collected before transfusion and 60 days or more after transfusion. Seroconversion was determined by a second-generation particle agglutination test. Confirmation tests were an immunofluorescence assay, enzyme-linked immunosorbent assay, and immunoblotting. Confirmed seroconverted patients were followed by a search of hospital records.

RESULTS

Seroconversion was found in one of 4672 transfused patients, but the donor was identified and confirmed to be negative for anti-HTLV-I and virus genome by nested polymerase chain reaction. A total of 23,323 red cell concentrates and 17,237 platelet concentrates were transfused to these 4672 patients. Therefore, the anti-HTLV-I prevalence in blood for transfusion after screening was estimated at 1 in 45,560 (0.0022%; the upper 95% CI was 0.0080%). One hundred two seroconverted patients who were transfused before donor screening for HTLV-I were followed. One patient developed HTLV-I-associated myelopathy, diagnosed 18 weeks after seroconversion, and another patient developed uveitis 1 month after seroconversion. No patients developed adult T-cell lymphoma, and the survival rate of seroconverted patients was 92.5 percent 15 years after transfusion.

CONCLUSION

This study confirmed that the present donor screening program for HTLV-I by the new particle agglutination test can almost completely prevent virus transmission by transfusion. Complications of HTLV-I transmission were at lower rates than expected.