OBJECTIVE: To evaluate the quality of serological screening of blood donors in five groups of blood banks in Latin America that participated over the 1997-2000 period in an external serology quality control project developed with support from the Pan American Health Organization (PAHO). METHODS: With assistance from PAHO, the Serology Authority of the Pro-Blood Foundation/Blood Center of São Paulo (Fundação Pró-Sangue/Hemocentro de São Paulo), of São Paulo, Brazil, carried out the external quality control project and served as its "organizing center" (OC). The OC developed five external serology quality control "programs" (ESQCPs), or external evaluation activities, for the respective groups of participating blood banks. There was one ESQCP each in 1997, 1999, and 2000, and there were two in 1998. In these five programs, the number of participating blood banks ranged from 13 to 21, and the number of countries ranged from 11 to 16. In each program, the OC used a set of 24 blinded sera samples with different reactivities for the various infectious agents for which screening is obligatory in Brazil. Each participating institution in each program received a sera set, to be processed using that institution's standard screening procedures. After returning its results to the OC, each participant received an answer key for the sera set, to be used in evaluating its own performance. All the individual results were kept strictly confidential. At the end of each program, the OC prepared and sent to all the participants a final report that contained information on the overall results from that program. RESULTS: An analysis of the five programs showed that there was a lack of homogeneity among the countries with respect to the strategies and the parameters used in screening blood donors. Few laboratories screened for human T-cell-lymphotropic virus (beginning with the 1997 program, the respective rates were 17%, 27%, 35%, 39%, and 45%). Rates of screening were also low for antibodies to the hepatitis B core antigen (again, beginning with the 1997 program, the rates were 42%, 27%, 39%, 50%, and 60%). There were also important differences with respect to which tests and which combinations of tests were used, making it hard to compare the types of screening done. In the five programs, with the various tests used, the overall rate of false positive results fluctuated around 2%. The highest false positive rate for any of the tests, 4.6%, was for antibodies against the hepatitis C virus. The lowest false positive rate, 0.4%, was for antibodies against Trypanosoma cruzi. CONCLUSIONS: These results show the need for PAHO to continue using these external quality control programs as well as other activities in order to strengthen the procedures for serological screening in blood banks in Latin America, until there is more uniformity in the procedures that the countries use.

OBJETIVOS: Con el apoyo de la Organización Panamericana de la Salud (OPS), desarrollamos entre 1997 y 2000 cinco programas de control externo de la calidad en serología (PCECS) en los que participaron entre 13 y 21 bancos de sangre de 11 a 16 países de América Latina. El objetivo fue evaluar el desempeño de los bancos de sangre con respecto al tamizaje serológico realizado en donantes de sangre. MÉTODOS: Como herramienta de trabajo utilizamos conjuntos de 24 muestras de sueros anónimos con reactividades variables para los parámetros de uso obligatorio en el tamizaje serológico de donantes de sangre en Brasil. En cada PCECS enviamos un multipanel a cada institución participante para que lo procesara en las mismas condiciones de su rutina de tamizaje. Cada participante recibió la clave del multipanel para autoevaluación, después de haber devuelto los resultados obtenidos en su laboratorio. Se mantuvo siempre la más estricta confidencialidad sobre los resultados obtenidos individualmente. Al terminar de cada programa, el Centro Organizador (Superintendencia de Serología de la Fundação Pró-Sangue/Hemocentro de São Paulo) elaboró un informe final que contenía toda la información obtenida en el programa y que fue enviado a los participantes. RESULTADOS: En el análisis de los cinco PCECS se observó falta de homogeneidad entre los países con respecto a las estrategias y a los parámetros utilizados en el tamizaje de donantes de sangre. Pocos laboratorios practicaron el tamizaje de los virus linfotrópico de células T humanas (HTLV) (17%, 27%, 35%, 39% y 45%, respectivamente y en orden creciente para los cinco PCECS) y de anticuerpos contra el antígeno nuclear del virus de la hepatitis B (anti-HBc) (42%, 27%, 39%, 50% y 60%). También se observaron diferencias importantes en cuanto a las pruebas o combinaciones de pruebas utilizadas, lo cual puede dificultar el estudio comparativo de los tipos de tamizaje. El número total de resultados positivos falsos osciló alrededor del 2%, correspondiendo el mayor valor al tamizaje de anticuerpos contra el virus de la hepatatis C (anti-VHC) (4,6%) y el menor a anti-Trypanosoma cruzi (0,4%). CONCLUSIONES: Los resultados obtenidos en este trabajo demuestran la necesidad de continuar las acciones de la OPS en América Latina para reforzar los procedimientos de tamizaje serológico en bancos de sangre, incluso los PCECS, hasta que se consiga una uniformidad de procedimientos en la Región de las Américas.

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.

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.

En otros estudios se ha evaluado el menor riesgo de infecciones transmitidas por transfusión sanguínea que acarrea el tamizaje de anticuerpos contra los antígenos nucleares de la hepatitis B (anti-HBc), sumado a la prueba detectora de antígenos de superficie (HbsAg). No obstante, la mayoría de estos estudios se basaron en datos procedentes de zonas con baja endemicidad por hepatitis B o de bancos de sangre de países desarrollados, donde la mayoría de la sangre proviene de personas que han donado previamente. A fin de examinar los pros y los contras del tamizaje de anticuerpos anti-HBc en el Brasil, los autores describen los antecedentes y la interpretación de las pruebas de tamizaje para prevenir la hepatitis postransfusión. También presentan los datos sobre el tamizaje de la hepatitis B en todas las regiones del Brasil. No hay pruebas suficientes para suspender el tamizaje de los anticuerpos anti-HBc en el país. Debe darse alta prioridad a comparar el costo-efectividad de un marcador basado en la biología molecular con el de la actual prueba detectora de anticuerpos anti-HBc aplicada comúnmente, a fin de mejorar las medidas de tamizaje que garantizan la inocuidad de la sangre.

No presente estudo, avaliamos a importância clínico-epidemiológica da genotipagem do VHC em 130 pacientes com diagnóstico histológico de hepatite crônica C e sua influência na resposta terapêutica sustentada. Não se observou associação entre os genótipos e os aspectos clínico-epidemiológicos como sexo, idade, vias de transmissão, presença ou não de cirrose e tempo de infecção. Dos 130 pacientes, 113 foram submetidos a tratamento com interferon-<FONT FACE="Symbol">a</FONT>-recombinante durante um período médio de 12 meses. A resposta completa, avaliada pela viremia e dosagem da ALT no término do tratamento, foi significativamente melhor nos portadores dos genótipos 2 (100%) e 3 (46%) do que nos portadores do tipo 1 (29%) (p < 0,005). Observou-se também diferença significativa quando se analisou a resposta completa entre os subtipos 1b e 2 (p < 0,005) e 1b e 3a (p < 0,05). A resposta sustentada (viremia negativa e/ou normalização da ALT ao sexto mês de monitoração pós tratamento) para os portadores dos genótipos 1a, 1b, 3a e 2 foi de 12%, 13%, 19% e 40%, respectivamente; houve diferença significativa entre os genótipos 1b e 2 (p < 0,001) e 1b e 3a (p < 0,05). Além disso, observou-se associação entre presença de cirrose e não resposta e resposta com recaída (p < 0,05). Portanto, o genótipo diferente de 1 e ausência de cirrose foram os únicos fatores que apresentaram associação à resposta terapêutica sustentada. Este estudo mostrou a importância da genotipagem na susceptibilidade ao tratamento da infecção crônica pelo VHC.

The present study assessed the clinical significance of hepatitis C virus (HCV) genotypes and their influence on response to long term recombinant-interferon-alpha (r-IFN-<FONT FACE="Symbol">a</FONT>) therapy in Brazilian patients. One hundred and thirty samples from patients previously genotyped for the HCV and with histologically confirmed chronic hepatitis C (CH-C) were evaluated for clinical and epidemiological parameters (sex, age, time of HCV infection and transmission routes). No difference in disease activity, sex, age or mode and time of transmission were seen among patients infected with HCV types 1, 2 or 3. One hundred and thirteen of them were treated with 3 million units of r-IFN-<FONT FACE="Symbol">a</FONT>, 3 times a week for 12 months. Initial response (IR) was significantly better in patients with genotype 2 (100%) and 3 (46%) infections than in patients with genotype 1 (29%) (p < 0.005). Among subtypes, difference in IR was observed between 1b and 2 (p < 0.005), and between 1b and 3a (p < 0.05). Sustained response (SR) was observed in 12% for (sub)type 1a, 13% for 1b, 19% for 3a, and 40% for type 2; significant differences were found between 1b and 2 (p < 0.001), and between 1b and 3a (p < 0.05). Moreover, presence of cirrhosis was significantly associated with non response and response with relapse (p < 0.05). In conclusion, non-1 HCV genotype and lack of histological diagnosis of cirrhosis were the only baseline features associated with sustained response to treatment. These data indicate that HCV genotyping may have prognostic relevance in the responsiveness to r-IFN-<FONT FACE="Symbol">a</FONT> therapy in Brazilian patients with chronic HCV infection, as seen in other reports worldwide.

O presente trabalho teve como objetivo estabelecer critérios adequados à triagem de doadores de sangue de regiões com características epidemiológicas distintas, para malária. Foram estudados 3 locais com critérios de seleção diferentes: São Paulo, SP (sem transmissão vetorial), Belém (baixa transmissão ativa), Matupá, Belém, PA e Peixoto de Azevedo, MT (alta transmissão ativa). A pesquisa de plasmódios foi realizada por gota espessa, QBC Test® e imunofluorescência para pesquisa de antígenos, tendo sido todas as amostras negativas. Houve grande variação na positividade para anticorpos antiplasmodiais por IFI-IgG anti P. vivax e P. falciparum entre doadores aptos nos 3 locais de estudo e entre doadores aptos e inaptos em São Paulo (aptos 1,98%, inaptos 22,3%, p < 0.01) e Belém (aptos 17,2%, inaptos 58,3%, p < 0.01), o que atesta a validade da triagem clínico-epidemiológica realizada. Em Matupá e Peixoto de Azevedo não houve doadores inaptos e a positividade foi de 80,6%. Consideramos que em bancos de sangue a triagem deve seguir critérios clínico-epidemiológicos adequados à situação de cada região. Os métodos laboratoriais de triagem, devem ser para detecção de plasmódios (gota espessa/QBC Test® ou detecção de antígenos parasitários.

The aim of the present work was to establish appropriate criteria for screening of donor blood from regions with distinct Malaria epidemiological characteristics. Three locations with different screening criteria were studied: São Paulo, SP (with no vectorial transmission), Belém, PA (with low active transmission) and Matupá and Peixoto de Azevedo, MT (with high active transmission). The Malaria parasite3/4Plasmodium sp3/4was searched for by "thick film", QBC Test( and antigen Immunofluorescence test, and was not detected in any of the samples. There was, however, a great variation in the positivity of anti-plasmodial antibodies, as determined by IIF-IgG anti-P. vivax and -P. falciparum, between accepted donors in the 3 studied locations and between rejected and accepted donors in São Paulo (1.98% accepted, 22.3% rejected - p < 0.01) and Belém (17.2% accepted, 58.3% rejected - p < 0.01). These data endorse the use of the applied clinical and epidemiological screening. In Matupá and Peixoto de Azevedo, where there was no rejected donor, the serological positivity was 80.6%. We, therefore, consider that the Malaria screening in blood banks should follow clinical and epidemiological criteria suitable to each region. The laboratorial screening techniques should then detect either the parasites (thick film/ QBC Test® or the parasite antigens.

A determinação do anticorpo de superfície contra a hepatite B (anti-HBs) precedendo a vacinação tem sido aconselhada com o intuito de encontrar indivíduos já imunes, para os quais esta administração seria desnecessária. Um caso clínico é aqui apresentado, juntamente com a revisão de três casos mencionados na literatura, nos quais o anti-HBs foi positivo em pessoal hospitalar, o que justificou sua não vacinação e ausência de medidas preventivas face contaminação pelo vírus B. Malgrado esta aparente proteção pela presença do anti-HBs eles desenvolveram hepatite aguda típica pelo vírus B. No primeiro caso da literatura a subtipagem revelou que o anti-HBs do passado e a infecção atual tinham determinantes d/y diferentes. Entretanto, os outros casos relatados mostravam ser o anti-HBs, dosado por radioimunoensaio (RIE), um falso positivo. Em nosso relato de caso o soro colhido no início da hepatite aguda foi re-testado por dois métodos diferentes e igualmente sensíveis. Observou-se persistência de positividade pelo RIE porém negatividade pelo enzimaimunoensaio (ELISA) A determinação concomitante de anti-HBs e anti-HBc ou ainda dos três marcadores é uma das alternativas propostas, enquanto que outra conduta seria a não realização de qualquer teste pré-vacinação. Acreditamos que o desenvolvimento tecnológico propiciará produção de vacinas menos dispendiosas e totalmente isentas de risco em futuro próximo.

The determination of anti-HBs as a screening test before vaccination has been advisable in order to encounter immune individuals that don't need to receive vaccine protection. A case-report is presented and three other cases are reviewed from the literature. Anti-HBs was positive in these health-care personnels that developped typical acute B hepatitis. Different subtyping involving the d/y determinants were found in the first case, but false-positive anti-HBs even with high titres, determined by RIA, were found in the other cases. Concomitant determination of anti-HBc or absence of screening tests seem to be more reasonable policies until a low-cost and risk-free vaccine is produced.