HTLV-1 antibody testing in a Saudi Arabian blood donor population

Human-T lymphotrophic virus Type 1 may be transmitted by cellular blood products. A low but definite risk exists that recipients of HTLV-1 infected products may develop severe even fatal disease. After one year of screening for HTLV-1 antibodies in 12,851 units of blood collected from a multinational volunteer donor population of which 42.6% were Saudi nationals, we found two units of blood which reacted repeatedly positive in the screen test. In both cases, the Western Blot confirmatory test was indeterminate in that not all bands required for a positive reaction were present. Both donors were expatriates from North America either living in an endemic area or with Caribbean ancestors. Although more than 5,000 Saudi national donors were tested and found negative for HTLV-1 antibodies, a statistical estimate of the maximal risk of finding a positive donor in this donor population subgroup is in the order of 0.055%. Based on these results it is recommended that blood banks in this region screen for HTLV-1.