Transfusion transmitted HTLV-1 and incidence of HTLV-1 in South African blood donors

HTLV-1 occurs world-wide but is more prevalent in some areas including southern Japan, the Caribbean region, parts of South America, Sub-Saharan Africa and the Middle East, Australia and Melanesia (1-3). The reason for this unusual geographical distribution is not known. An interesting aspect of this virus is that only a few nucleotide substitutions are observed among virus strains of HTLV-1. This variability of nucleotides is specific to the geographical origin of the patients. HTLV-1 was originally acquired by humans through interspecies transmission from STLV-1 (simian T-cell leukaemia virus type 1) infected monkeys in Africa, Europe and Asia (1).