OBJETIVOS: Conocer la proporción de sangre descartada por seropositividad al virus linfotrópico de células T humanas (HTLV) tipos I y II, la prevalencia de dicha infección y los probables factores de riesgo en donantes del Banco Municipal de Sangre de Caracas (BMSC). MÉTODOS: Se evaluaron serológicamente mediante ensayos de inmunoadsorción enzimática (ELISA) 23 413 donantes atendidos entre julio del año 2000 y abril de 2001 en el BMSC. Las muestras repetidamente reactivas (RR) se estudiaron por inmunoblot de Western (WB), como prueba suplementaria. Los donantes positivos o indeterminados por WB fueron citados a la consejería para realizar la confirmación mediante la amplificación de ácidos nucleicos por reacción en cadena de la polimerasa (PCR), recoger datos sobre sus antecedentes de riesgo y asesorarlos acerca de su estado. RESULTADOS. El 0,2% de las donaciones resultaron RR; de ellas 52,1% resultaron positivas en el WB (23 a HTLV I y 2 a HTLV II); 4,1% indeterminadas por WB; 29,2% negativas; y el 14,6% no pudo ser evaluado. Asistieron a la consejería 16 donantes (14 WB positivos a HTLV I, 1 a HTLV II y 1 indeterminado). Todos resultaron positivos en la RCP. No se encontraron diferencias significativas con el grupo control en cuanto a edad, sexo, tipo de donación, número de donaciones previas, antecedentes de transfusiones y comportamiento sexual. Se observaron diferencias significativas según los antecedentes de consumo de drogas no intravenosas (P < 0,05), y altamente significativas (P < 0,001) según los antecedentes de lactancia materna larga. Las madres estudiadas de seis de los donantes positivos que manifestaron haber tenido una larga lactancia materna resultaron positivas, al igual que el hijo mayor de la única pareja positiva de las 13 evaluadas. CONCLUSIONES. Se descartó el 0,2% de la sangre por resultar positiva al HTLV I/II. La prevalencia entre los donantes fue de 0,11%. En el 37,5% de los casos se pudo determinar la probabilidad de transmisión de madre a hijo. La transmisión sexual resultó menos frecuente. Se debe considerar seriamente la implementación del tamizaje serológico del HTLV I/II en los donantes de sangre de Venezuela.

OBJECTIVE: To conduct research at the Municipal Blood Bank of Caracas (MBBC) and find out the proportion of blood units discarded for being seropositive for human T-lymphotropic virus (HTLV) types I and II, the prevalence of that infection among their donors, and the probable risk factors for that infection among those HTLV-positive donors. METHODS: ELISA serological testing was done with 23 413 donors seen at the MBBC between July 2000 and April 2001. Samples that were repeat reactive (RR) with the ELISA underwent supplementary Western blot (WB) testing. Donors who had a positive or indeterminate WB result were scheduled for counseling in order to carry out confirmatory testing using nucleic acid amplification (NAA), to collect data on their risk background, and to advise them concerning their HTLV status. RESULTS: Of the 23 413 MBBC donors, 48 of them (0.2%) had a donation that was RR. Of those 48, 25 of them (52.1%) were positive on the WB (23 for HTLV-I and 2 for HTLV-II), 2 of them (4.1%) were indeterminate on the WB, 14 of them (29.2%) were negative, and 7 (14.6%) could not be evaluated. Of the 27 donors scheduled for counseling, 16 of them actually attended (14 WB-positive for HTLV-I, 1 WB-positive for HTLV-II, and 1 indeterminate). All 16 of them were positive with the confirmatory NAA testing. When these 16 seropositive donors were compared with a control group of seronegative donors, no significant differences were found with regard to age, sex, type of donation, number of previous donations, history of transfusions, and sexual behavior. However, significant differences were found in two areas: the seropositive donors were more likely to have used non-intravenous drugs (P < 0.05), and the seropositive donors were much more likely to have had an extended breast-feeding period (more than 2 years) as a child (P < 0.001). To assess the probability of mother-to-child transmission, six of the mothers of seropositive donors who had had an extended breast-feeding period were tested, and all six of those mothers were also found to be seropositive. With the 16 seropositive donors who were counseled, the spouse or partner of 13 of them was also tested; only 1 of those 13 was positive, but the oldest son of that couple was also HTLV-positive. CONCLUSIONS: Of the donated blood, 0.2% of the units were discarded for being positive for HTLV-I or HTLV-II, and the prevalence found among the donors was 0.11%. Sexual transmission between an HTLV-positive donor and a partner or spouse was less frequent than was mother-to-child transmission. At present in Venezuela, blood banks are not required to screen donations for HTLV. Given our results at the MBBC, we believe serious consideration should be given to implementing serological screening for HTLV I/II among blood donors throughout Venezuela.