HTLV-I AMONG NORTHERN-TERRITORY BLOOD-DONORS

Objective; Human T-lymphotropic virus type I (HTLV-I) is known to be e ndemic among Northern Territory (NT) Aborigines, therefore evidence wa s sought of HTLV-I infection in NT blood donors. Design: Samples were screened for HTLV-I antibodies using the Serodia HTLV-I particle-agglu tination assay. Repeatedly reactive sera were tested by western blot. Viro- logical and molecular investigations were also performed. Sera: Aliquots from all 11 121 blood donations collected between June 1991 a nd August 1992. Results: Four (0.036% of total) blood donations, each from different donors, were repeatedly reactive by particle-agglutinat ion assay. One (0.009%) sample, from a 52-year-old non-Aboriginal man with no verified risk factors, was confirmed as HTLV-I seropositive by western blot. A viral isolate and a 431 base pair polymerase chain re action product from the env gene were obtained from a culture of his p eripheral blood mononuclear cells. Sequencing of the polymerase chain reaction product demonstrates that this isolate is a prototype strain and not the variant identified among Aborigines. The remaining three r epeatedly reactive donors, including the positive donor's wife, were w estern blot indeterminate. Conclusions: There is a low prevalence of H TLV-I carriage among blood donors in the NT, and presumably in other S tates. However, most repeatedly reactive donations prove to be western blot indeterminate, therefore additional tests are required to detect or exclude HTLV-I infection. Although universal screening of donation s would virtually eliminate HTLV-I transmission by transfusion, it has disadvantages, including financial cost.