• Seropositivity for human T-lymphotropic virus types I and II among donors at the Municipal Blood Bank of Caracas and associated risk factors Experiencias Nacionales

    León, Graciela; Quirós, Ana M.; López, José L.; Hung, Meilyn; Díaz, Ana M.; Goncalves, Juvic; Costa, Osiris da; Hernández, Teodoro; Chirinos, Merlin; Gómez, Rafael

    Abstract in Spanish:

    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.

    Abstract in English:

    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.
  • The results of an external quality control program for serological screening for antibodies against Trypanosoma cruzi in blood donors in Brazil Experiencias Nacionales

    Sáez-Alquézar, Amadeo; Murta, Márcia; Marques, Waldelania Pereira; Silva, Guilherme Rodrigues da

    Abstract in Spanish:

    OBJETIVOS: A partir de 1995 en Brasil se iniciaron programas de control de calidad externo de laboratorios de serología (PCCES) abiertos a la participación de laboratorios de bancos de sangre públicos y privados. Estos programas se han puesto en práctica tres veces al año desde 1995 y cuentan con la participación de más de 100 entidades. El objetivo de este trabajo es analizar los resultados de los ocho últimos programas de evaluación del tamizaje serológico para la enfermedad de Chagas, que se realizaron entre abril de 1999 y agosto de 2001. MÉTODOS: Participaron en los ocho programas laboratorios de serología de instituciones públicas y privadas. El número de laboratorios participantes que entregó los resultados en cada uno de los ocho PCCES fue de 94, 90, 85, 94, 100, 103, 102 y 116, respectivamente. Al inicio de cada PCCES se envió un panel enmascarado a cada institución participante, con un plazo de 60 días para informar los resultados del procesamiento de las muestras. Se utilizaron pruebas de inmunoadsorción enzimática (ELISA), inmunofluorescencia indirecta (IFI) y hemaglutinación indirecta (HAI). Posteriormente, cada institución recibió del centro organizador (PANEL) la clave con los resultados correctos para su autoevaluación. Los paneles estaban compuestos por 24 muestras de sueros con diferentes reactividades a los marcadores obligatorios en el tamizaje serológico de donantes de sangre en Brasil, incluido el de muestras negativas. RESULTADOS: La técnica de ELISA fue la más utilizada en el tamizaje (92%-98%). La estrategia de tamizaje más usada por los laboratorios participantes fue la combinación de una prueba de ELISA y una de HAI (58%-83%). La mayoría de los laboratorios participantes obtuvieron resultados correctos en los diferentes programas sin resultados negativos falsos (83,6%-98,1%). De las 5 406 muestras de suero positivas a anti-Trypanosoma cruzi que hubo en los ocho programas, 85 (1,6%) fueron notificadas de negativas por 58 laboratorios, pero solamente 14 de ellos dejaron de identificar una o más muestras positivas por no conseguir detectarlas por medio de ninguna de las pruebas de tamizaje utilizadas. No se observó ninguna diferencia significativa entre bancos en los ocho programas (P = 0,5936). No se observó asociación entre los resultados negativos falsos y una muestra o sistema diagnóstico en particular. La técnica de HAI presentó el mayor número de resultados negativos falsos (0,7%-7,9%). De los 32 855 resultados obtenidos en muestras de sueros negativas a anti-T. cruzi en los ocho programas, 106 (0,32%) fueron notificados como resultados positivos falsos. Entre 1% y 16% de los laboratorios participantes obtuvieron un resultado positivo falso por programa y entre 0% y 4% notificó más de un resultado positivo falso. La proporción de resultados negativos falsos muestra una tendencia descendente después de 1995. CONCLUSIONES: Los resultados obtenidos en este trabajo apuntan hacia una tendencia desecendente en la proporción de resultados negativos falsos. Al mismo tiempo se observó que la técnica de HAI continúa arrojando el mayor número de resultados negativos falsos. Se sugiere darle preferencia a la técnica ELISA para el tamizaje de donantes de sangre.

    Abstract in English:

    OBJECTIVES: In 1995 a series of external quality control programs (EQCPs) was launched for serology laboratories in Brazil, open to both public and private blood-bank laboratories. These "programs" have been held several times per year since 1995. The objective of this paper is to present the results achieved during eight programs conducted between April 1999 and August 2001, in terms of serological screening for Chagas' disease. METHODS: The participants in these eight EQCPs were serology laboratories from public and private institutions. The number of participants in each respective program that sent in its results was 94, 90, 85, 94, 100, 103, 102, and 116. At the beginning of each EQCP a blinded panel of sera was sent to each participating institution. Each panel consisted of 24 serum samples with different reactivities for the markers for which the serological screening of blood donors is obligatory in Brazil; among the 24 samples were some negative ones. The participants had 60 days to complete their testing and send in their results for evaluation. Later, each participant received an answer key for the sera panel, to use in self-evaluation. RESULTS: The three tests that the participants used most frequently were enzyme-linked immunosorbent assay (ELISA), indirect hemagglutination (IHA), and indirect immunofluorescence (IIF). Of these three, the ELISA was used most often, ranging from 92% to 98% of the laboratories for the eight programs. The screening strategy that was most often used was a combination of an ELISA test and an IHA test (ranging from 58% to 83% of the laboratories for the eight programs). In the various programs, the large majority of participating laboratories (range, 83.6%-98.1%) obtained accurate results without any false negative results. Of the 5 406 tests carried out during the eight programs using positive anti-T. cruzi sera samples, 85 (1.6%) were reported as negative in 58 laboratories. However, only 14 of those laboratories were unable to identify one or more positive samples after using all their screening tests. There were no significant differences found between the blood banks in the eight programs (P = 0.5936). No association was found between false negative results and any particular sample or any specific diagnostic kit. IHA testing had the highest proportion of false negatives, ranging from 0.7% to 7.9% for the eight programs. Of 32 855 tests performed during the eight programs using negative anti-T. cruzi sera, 106 (0.32%) were reported as false positives. The percentage of participating laboratories that had one false positive result per program varied from 1% to 16%, and between 0% and 4% of the labs per program had more than one false positive result. In comparison to testing done in Brazil in 1994-1995, the proportion of false negative results has declined. CONCLUSIONS: The results of this study point to a decrease over time in the proportion of false negative results. In the 1999-2001 programs, the highest percentage of false negative results was found with IHA testing. Therefore, it is recommended to give preference to ELISA testing for screening blood donors.
  • External evaluation of serology results in blood banks in Colombia Experiencias Nacionales

    Beltrán Durán, Mauricio; Ayala Guzmán, Maribel

    Abstract in Spanish:

    OBJETIVO: Analizar los resultados serológicos obtenidos en los bancos de sangre colombianos que participan en el programa externo de calidad (PEC) con el fin de mejorar la calidad del tamizaje de la sangre según los principales marcadores serológicos de enfermedades infecciosas de posible transmisión sanguínea. MÉTODOS: Se evaluó un panel de seis sueros con diferente reactividad y positividad a anticuerpos contra los virus de la inmunodeficiencia humana (VIH) 1-2, el virus de la hepatitis C (VHC), Trypanosoma cruzi, Treponema pallidum y el virus linfotrópico de células T humanas (HTLV), y contra el antígeno de superficie del virus de la hepatitis B (HBsAg). Las técnicas de tamizaje utilizadas fueron el ensayo de inmunoadsorción enzimática (ELISA), el inmunoensayo enzimático de micropartículas (MEIA) y la hemaglutinación (HA). Se solicitó a los bancos de sangre participantes que aplicaran a los sueros las pruebas que diariamente realizaban para el tamizaje de unidades de sangre y que enviaran los resultados a la Coordinación Nacional de Bancos de Sangre del Instituto Nacional de Salud de Colombia. RESULTADOS: De 46 bancos de sangre que participaron, 43 (93%) devolvieron los resultados en el plazo indicado. La prueba de ELISA fue la más utilizada (83,02%). Se obtuvo un total de 49 (5%) resultados positivos falsos y 12 (3%) resultados negativos falsos. De estos últimos, 50% correspondieron a la detección de la sífilis; 16,7% a la de la enfermedad de Chagas; 16,7% a la de anticuerpos anti-HBc; 8,3% a la de anticuerpos anti-VHC y 8,3% a la del HBsAg. Ochenta por ciento de los resultados discordantes se presentaron en 23 bancos de sangre con un volumen de menos de 6 000 unidades de sangre al año, y 15% en 5 bancos de sangre con un volumen de 6 000 a 12 000 unidades de sangre al año. De los bancos de sangre que recogían más de 12 000 unidades anuales, solo uno notificó tres resultados positivos falsos. No se notificaron resultados negativos falsos. CONCLUSIONES: El porcentaje de resultados negativos falsos (3%) obtenidos durante el PEC puede considerarse elevado, ya que las pruebas que resultan negativas durante el tamizaje de los bancos de sangre no se repiten y la decisión de declarar una unidad de sangre apta para transfusión se basa en ese único resultado. Es preciso revisar minuciosamente los procedimientos para el tamizaje de la sangre, en particular en aquellos centros que tuvieron un desempeño pobre.

    Abstract in English:

    OBJECTIVE: To analyze the serological results found in Colombian blood banks that participate in the external quality program (EQP) of that country's National Institute of Health, in order to improve the quality of the screening of blood for the main serological markers of transfusion-transmitted infectious diseases. METHODS: Each blood bank received a panel of six sera with different reactivity and positivity to hepatitis B surface antigen (HBsAg), as well as to antibodies to HIV 1-2, Trypanosoma cruzi (the causative agent of Chagas' disease), Treponema pallidum (the causative agent of syphilis), hepatitis B core (HBc) antigen, hepatitis C virus (HCV), and human T-lymphotropic virus (HTLV). The screening techniques used were enzyme- linked immunosorbent assay (ELISA), microparticle enzyme immunoassay (MEIA), and hemagglutination. With the panel sera, the participating blood banks were asked to apply the same tests that they use on a daily basis to screen blood units and to send their results to the National Blood Banks Unit of the Colombian National Institute of Health. RESULTS: Of the 46 blood banks participating in the EQP, 43 of them (93%) returned their results within the requested timeframe. The ELISA test was the one that was used most often (83.0%). There were a total of 49 (5%) false positive results and 12 (3%) false negative results. Of those 12 false negative results, 6 of them corresponded to the detection of syphilis, 2 to Chagas' disease, 2 to anti-HBc antibodies, 1 to anti-HCV antibodies, and 1 to HBsAg. Eighty percent of the discordant results came from 23 blood banks that each collected fewer than 6 000 units of blood per year, and 15% came from 5 blood banks that collected 6 000 to 12 000 units per year. One of the blood banks that collected more than 12 000 units annually had three false positive results, and none of those larger blood banks had any false positive results. CONCLUSIONS: The percentage of false negative results (3%) found during the EQP can be considered high, since tests that are negative during blood screening are not repeated, and the decision to declare a unit of blood suitable for transfusion is based on that single result. There is a need to thoroughly review the procedures for screening blood in Colombia, particularly at the centers that performed poorly in this EQP exercise.
  • External performance evaluation of screening in blood banks in Argentina: results and strategies for improvement Experiencias Nacionales

    Oknaian, Sebastián; Remesar, Mirta; Ferraro, Laura; Pozo, Ana Emilia del

    Abstract in Spanish:

    OBJETIVOS: Debido a la falta de un programa para la evaluación externa de la calidad del tamizaje de infecciones transmisibles por transfusión (ITT) en los bancos de sangre, el Servicio de Hemoterapia del Hospital Garrahan, de Buenos Aires, Argentina, inició en 1999 un programa continuo con el apoyo de la Organización Panamericana de la Salud (OPS) y la Asociación Argentina de Hemoterapia e Inmunohematología (AAHI). MÉTODOS: Se distribuyó un panel de 12 muestras con reactividad para todos los marcadores tamizados en los bancos de sangre argentinos. El panel se entregó a 52, 102 y 118 laboratorios en 1999, 2000 y 2001, respectivamente. Los laboratorios participantes se clasificaron según su desempeño en: A: menos de 2 resultados positivos falsos (RPF); B: de 2 a 3 PF; C: más de 3 RPF; y D: algún resultado negativo falso. Se efectuaron talleres con los participantes para analizar conjuntamente los resultados. RESULTADOS: Los porcentajes de respuesta de cada año fueron 92,3, 92,2 y 83,9, respectivamente; estos porcentajes de respuesta indican interés en las actividades de evaluación. Sin embargo, el promedio de los laboratorios con clasificación D resultó muy alto (30%), lo que evidencia la presencia de problemas en el desempeño del tamizaje de las ITT. Esto podría asociarse con la dificultad de tomar medidas correctoras en todo el sistema, dado el elevado número de laboratorios involucrados. CONCLUSIONES: Se deben incluir evaluaciones de este tipo en el Programa Nacional de Sangre para el diagnóstico continuo de la situación, la toma de decisiones y el seguimiento de la calidad del tamizaje.

    Abstract in English:

    OBJECTIVES: Because there was no program for the external evaluation of the quality of the screening for transfusion-transmitted infections (TTIs) in blood banks in Argentina, in 1999 the Hemotherapy Service of Garrahan Hospital, in Buenos Aires, launched an ongoing external evaluation program, with the support of the Pan American Health Organization and the Argentine Hemotherapy and Immunohematology Association. METHODS: A panel of 12 samples that were reactive to all the markers screened for in Argentine blood banks was distributed. The panel was delivered to 52 laboratories in 1999, 102 laboratories in 2000, and 118 laboratories in 2001. The participating laboratories were classified into one of four categories according to their performance: A: 0 or 1 false positive (FP) results; B: 2 or 3 FPs; C: 4 or more FPs; and D: at least 1 false negative result. Workshops were held with the participants in order to jointly analyze the results. RESULTS: Out of the laboratories that received the panel of samples, the percentage of laboratories that sent in their results was 92.3% in 1999, 92.2% in 2000, and 83.9% in 2001. These response levels demonstrate the interest in evaluation activities. However, the annual average percentage of the laboratories that received a "D" classification was very high (30%), which indicates that there are problems in the performance of TTI screening. This poor showing could be related to the difficulty in taking corrective measures throughout the system, given the large number of laboratories involved. CONCLUSIONS: Evaluations of this type should be included in Argentina's National Blood Program as a tool for the ongoing assessment of the blood banking situation, for decision-making, and for monitoring the quality of screening.
  • The Transfusion Medicine Program in Cuba Experiencias Nacionales

    Santovenia, José M. Ballester

    Abstract in English:

    Cuba's Transfusion Medicine Program (TMP) is a subsystem of the country's National Health System. The TMP's objective is to ensure hemotherapy with blood that is safe and sufficient for all the individuals who need it. The TMP subsystem is made up of the National Commission on Transfusion Medicine, the Institute of Hematology and Immunology, 37 clinical services, 44 blood banks, 120 collection centers, 19 mobile units, and 37 blood certification laboratories. Additional facilities include a laboratory for plasma separation, a laboratory that produces leukocyte interferon and transfer factor, and two laboratories that produce reagents for blood classification and blood diagnosis systems. In Cuba, blood donation is voluntary. Since 1997 approximately 5% of the population per year has donated blood, thus meeting the goal recommended by the Pan American Health Organization of one voluntary blood donation annually for every 20 persons. During 2002, 563 204 blood donations were received, and there were 445 898 transfusions of blood or blood components. All donations are individually screened for HIV 1 and 2, hepatitis B, hepatitis C, and syphilis, thus meeting the country's current regulations. In 2002 these screening measures led to discarding, respectively, 0.12%, 0.60%, 0.71%, and 1.8% of the blood donations. Although the prevalence of human T-cell lymphotropic virus I and II in Cuba is very low, this test will soon be added to the screening process.
  • Peru's experience with a national blood banking program Experiencias Nacionales

    Rivera Salcedo, José Fuentes; Roca Valencia, Oscar

    Abstract in English:

    This paper describes Peru's experiences with its National Blood Banking Program. Until the mid-1990s, the country faced a host of problems, including the lack of a legal framework to regulate blood banks, a high maternal mortality rate due to a shortage of blood, virtually no voluntary donations, a high risk of infection from transfusions, the use of only whole blood for transfusion, serious disorganization in the blood banks, deficiencies in blood bank supervision and control, no training programs, indifference on the part of health officials, frequent selling of blood, and limited community awareness. Subsequently, a strategic plan was prepared that made it possible to solve many of those problems. Legal instruments were prepared; the rate of voluntary donations rose from 0% to 19.5%; the safety of the blood was improved through compulsory screening of all donated blood units for seven markers of infectious diseases, as well as by placing a national seal of quality on all screened units. The availability of blood doubled, thus meeting 70% of the need; sales of blood decreased; and the use of blood components was improved, with 80% of the blood being fractionated. In addition, supervisory control of 100% of the blood banks in the country was achieved, a national registry was established, the cost-benefit relationship for blood units was improved through centralized screening, internal and external quality control was made mandatory, and prodonation campaigns led to commitments from civil society. While important, all these achievements represent just a first step. This is especially true given that developing the National Blood Banking Program required the participation of outside organizations, such as the Pan American Health Organization, whose support, together with the experience provided by other countries, was key. The Program is facing a number of new challenges, and the progress that has been achieved could be threatened if current activities stagnate or if officials become complacent.
Organización Panamericana de la Salud Washington - Washington - United States
E-mail: contacto_rpsp@paho.org