Bimodal distribution of Trypanosoma cruzi antibody levels in blood donors from a highly endemic area of Argentina: what is the significance of low-reactive samples?

BACKGROUND: Low-level seroreactive donor samples that are inconsistently detected by different Trypanosoma cruzi immunoassays are common, but the population distribution has not been reported in an endemic region. The objective was to understand the distribution of low-level reactive samples using highly sensitive immunoassays and the relationship with epidemiologic evidence of exposure to T. cruzi. STUDY DESIGN AND METHODS: Blood donors (BDs) were recruited in two blood banks located in Chaco province, in northeastern Argentina, from June 2006 to March 2007. Donors completed a Chagas exposure questionnaire and provided blood samples. All samples were tested in parallel with five contemporary and commercially available enzyme immunoassays for T. cruzi and a subgroup by a chemiluminescent assay. RESULTS: Of the 1423 enrolled donors, 304 (21.4%) tested positive on all assays while 93 (6.5%) were reactive on at least one assay (inconclusive). Epidemiologic evidence of exposure to T. cruzi was significantly higher among positive and inconclusive donors compared to seronegative BD (p values range from 0.01 to <0.001 depending on the exposure). Histograms of the signal-to-cutoff values from all positive samples showed clear bimodal distributions for the whole parasite lysate assays, but not for the one recombinant antigen-based assay. Low antibody level responses were present in 30% to 40% of the reactives, depending on the assay. CONCLUSION: The population of individuals exposed to T. cruzi in highly endemic regions has a bimodal distribution of antibody response to the parasite. Although the clinical significance of low-level reactivity is not fully established, these results may reflect evolving seroreversions after spontaneously resolved infections.

A comprehensive protocol to evaluate the use of blood and its components in Latin America and the Caribbean.

Blood transfusion safety is a critical part of appropriate health care. Considering the limited information available on the use of blood and its components in Latin America and the Caribbean, the Grupo Cooperativo iberoamericano de Medicina Transfusional (Ibero-American Cooperative Group for Transfusion Medicine; GCIAMT), through its Research and International Affairs committees, carried out a project to develop a protocol that would facilitate the evaluation of blood usage at the country, jurisdiction, and institutional levels in varied country contexts. Experts in blood safety from the Pan American Health Organization (Washington, DC, United States), the University of São Paulo (São Paulo, Brazil), the Hemocentro of São Paulo (São Paulo, Brazil), and GCIAMT designed a 2-step comprehensive blood-use evaluation protocol: step 1 collects data from blood requests, and step 2, from medical charts. At a minimum, 1 000 analyzed requests are necessary; as such, study periods vary depending on the number of transfusion requests issued. An Internet-based application, the Modular Research System-Study Management System (MRS-SMS), houses the data and produces reports on how hospitals request blood, how blood is issued, who requires blood and blood components, and as an added benefit, how many blood units are wasted and what the real demand for blood is.

Estimation of sensitivity and specificity of several Trypanosoma cruzi antibody assays in blood donors in Argentina.

BACKGROUND: The absence of a gold standard test for Trypanosoma cruzi antibodies represents a problem not only for the evaluation of screening tests, but also for appropriate blood donor counseling. The aim of this study was to estimate the sensitivity and specificity of multiple blood donor screening tests for T. cruzi antibodies in Argentina. STUDY DESIGN AND METHODS: From June 2006 to March 2007 a sample of 1455 blood donors was recruited from two blood banks in Chaco province, an area of Argentina with highly endemic T. cruzi infection. Samples were tested by three epimastigote lysate enzyme immunoassays (EIAs), one recombinant antigen EIA, two indirect hemagglutination assay (IHA) tests, a particle agglutination assay (PA), and a research trans-sialidase inhibition assay (TIA). Sensitivity and specificity were estimated using latent class analysis (LCA). RESULTS: LCA estimated the consensus prevalence of T. cruzi infection at 24.5%. Interassay correlation was higher among the four EIA tests and TIA compared to IHA tests. Assay sensitivities varied from 96 to 99.7 for different EIAs, 91% for TIA, 84% for PA, and 66 to 74% for IHA tests. Relative to the LCA, assay specificities were from 96% to almost 100%. CONCLUSION: Based on the comparison of several tests in a large population from an endemic area for T. cruzi infection, our data showed an adequate sensitivity for EIA tests in contrast to PA and IHA assays. The latter tests should no longer be used for blood donor screening.

Relevance of HTLV-1 proviral load in asymptomatic and symptomatic patients living in endemic and non-endemic areas of Argentina.

HTLV-1 proviral load (pVL) in peripheral blood mononuclear cell (PBMCs) is proposed as a marker of disease progression but its role still remains controversial. The aim of this study was to evaluate the levels of HTLV-1 pVL in symptomatic patients and asymptomatic HTLV-1 carriers. In this cross-sectional study the pVL was measured by Real Time PCR in 102 asymptomatic carriers and 22 symptomatic patients (5ATLL, 15 TSP and 2 uveitis). We observed that the HTLV-1 pVL was significantly higher in symptomatic patients (median = 4.99 log10 HTLV-1 copies /106 PBMCs) compared to asymptomatic HTLV-1 carriers (median = 4.38 log10 HTLV-1 copies /106 PBMCs; p = 0.0030). A wide variation on the HTLV-1 pVL levels among asymptomatic HTLV-1 carriers was observed with some pVL as high as those observed in symptomatic patients. The asymptomatic HTLV-1 carriers were divided according to the place of birth and the highest levels of pVL were detected among patients from endemics areas from the North of Argentina. Our results reinforce the usefulness of the proviral load would be a prognostic marker of HTLV-1 disease progression. Moreover, host, viral or socio-environmental factors cannot be excluded as determinant of high proviral load.

Inmunoensayo quimioluminiscente para sífilis en donantes de sangre: ¿Los valores de lectura se correlacionan con el estado de la infección? / Chemiluminescent immunoassay for syphilis in blood donors: do signal strength values correlate with the infection status? / Imunoensaio quimioluminescente para sífilis em doadores de sangue: os valores de leitura estão correlacionados com o estado da infecção?

Resumen El objetivo del trabajo fue comparar el desempeño del tamizaje treponémico y no treponémico en dos períodos próximos en el tiempo en donantes de sangre y analizar la asociación de la intensidad de la señal de la prueba quimioluminiscente (QL) con la reactividad del enzimoinmunoanálisis (ELISA) y la reagina plasmática rápida (RPR). Se realizó el tamizaje con pruebas treponémicas. Se analizó la distribución de los valores de señal/valor de corte (S/CO) obtenidos por QL en función del ELISA y RPR y se evaluó su asociación entre dos grupos de resultados de laboratorio (1) ELISA+/RPR+ y (2): ELISA+/RPR-. Se procesaron 76 794 donaciones voluntarias. Al comparar las medianas entre grupos, se encontró que la relación S/CO de QL fue significativamente mayor para los donantes del Grupo 1 (19,5 vs. 8,10; p<0,001). Se concluye que la intensidad de la señal de la prueba cualitativa QL estaría asociada con la reactividad de la RPR y guardaría relación con el curso de la infección.

Abstract The objective of this work was to compare the performance of treponemal and non-treponemal screening in two periods close in time in blood donors and to analyse the association of the signal strength (signal-to-cutoff, S/ CO) of the chemiluminescent immunoassay (CIA) with the reactivity of the enzymeimmunoassay (EIA) and the rapid plasma reagin (RPR). Donors were screened with treponemal tests. The distribution of the S/CO values obtained by CIA was analysed based on EIA and RPR, and its association was evaluated. Group 1: ELISA+/RPR+ donors and Group 2: ELISA+/RPR-. A total of 76,794 voluntary donations were processed. Comparing the means between groups, it was found that the CIA S/CO ratio was significantly higher for Group 1 donors (19.5 vs. 8.10; p<0.001). In conclusion, the signal strength of the qualitative CIA test would be associated with the reactivity of the RPR and would be related to the course of the infection.

Resumo O objetivo do trabalho foi comparar o desempenho da triagem treponêmica e não treponêmica em dois períodos próximos no tempo em doadores de sangue e analisar a associação da intensidade do sinal da prova quimioluminescente (QL) com a reatividade da análise imunoenzimática (ELISA) e a reagina plasmática rápida (RPR). Foi realizada uma triagem com provas treponêmicas. Foi analisada a distribuição dos valores de sinal/valor de corte (S/CO) obtidos por QL em função da ELISA e RPR, e também a associação entre dois grupos de resultados laboratoriais (1): ELISA+/RPR+ e (2) ELISA+/ RPR-). Foram procesadas 76 794 doações de sangue voluntárias. Ao comparar as medianas entre os grupos, obteve-se que a relação S/CO de QL foi significativamente maior para os doadores de sangue do grupo 1 (19,5 vs. 8,10; p<0,001). Em conclusão, a intensidade do sinal da prova qualitativa QL estaria associada com a reatividade da RPR e guardaria relação com o curso da infecção.

Antibodies to hepatitis C and other viral markersin multi-transfused patients from Argentina.

BACKGROUND: The knowledge of transfusion-transmitted viral infections in Argentina is scarce. A regional study organized by the Pan American Health Organization let us asses the current status. OBJECTIVES: To estimate the prevalence of HCV, HBV and HIV infection in a population of multi-transfused Argentinean patients. STUDY DESIGN: Multi-center, cross sectional study of 504 patients from national referral institutions in Buenos Aires, who had received more than ten units of blood products in more than two occasions. Demographic and clinical data were collected using a standardized questionnaire. Blood samples were analyzed for a-HCV, a-HIV, HBsAg and a-HBcore. RESULTS: Patients belonged to five diagnostic categories: onco-hematology (309; 61.3%); hemophilia (96; 19%); acute blood loss (54; 10.7% ); hemoglobinopathies (35; 6.9%); and hemodialysis (5; 1% ); five patients (1%) had two of the previous conditions. Overall prevalence rates of viral markers were: a-HCV 9.3% (CI(95%): 6.7-12.0); a-HBcore 4.8% (CI(95): 2.8-6.7); a-HIV 1.2% (CI(95%): 0.14-2.2) and HBsAg 0.20%(CI(95%): 0.2-0.59). The highest prevalence rates were found among patients living with hemophilia (PLH). There was a significant statistical association (p < 10(-5), OR =78.8 [29.7-209.7]) between a-HCV infection and having been transfused before 1993, when screening blood donors for a-HCV became mandatory in our country. The subpopulation of patients exposed to transfusion before 1993 was conformed mostly by PLH (70.9%) and hemoglobinopathies (18.6%). In this subpopulation, we found a significant association (p < 10(Dot;), OR -40 [5.68-281.66]) between years of exposure to transfusion and a-HCV among the patients under the median age (21.95 years old); however, there was no association for those above the median age (p=0.111). CONCLUSION: a-HCV was found to be the most prevalent infection in the multi-transfused patient population under study. Most infected individuals were PLH, transfused before 1993. This study will provide support for further research aimed at improving blood safety in Argentina.

A comprehensive protocol to evaluate the use of blood and its components in Latin America and the Caribbean / Un protocolo integral para evaluar el uso de la sangre y sus componentes en América Latina y el Caribe

Blood transfusion safety is a critical part of appropriate health care. Considering the limited information available on the use of blood and its components in Latin America and the Caribbean, the Grupo Cooperativo iberoamericano de Medicina Transfusional (Ibero-American Cooperative Group for Transfusion Medicine; GCIAMT), through its Research and International Affairs committees, carried out a project to develop a protocol that would facilitate the evaluation of blood usage at the country, jurisdiction, and institutional levels in varied country contexts. Experts in blood safety from the Pan American Health Organization (Washington, DC, United States), the University of São Paulo (São Paulo, Brazil), the Hemocentro of São Paulo (São Paulo, Brazil), and GCIAMT designed a 2-step comprehensive blood-use evaluation protocol: step 1 collects data from blood requests, and step 2, from medical charts. At a minimum, 1 000 analyzed requests are necessary; as such, study periods vary depending on the number of transfusion requests issued. An Internet-based application, the Modular Research System-Study Management System (MRS-SMS), houses the data and produces reports on how hospitals request blood, how blood is issued, who requires blood and blood components, and as an added benefit, how many blood units are wasted and what the real demand for blood is.

La seguridad de las transfusiones de sangre constituye una parte fundamental de una apropiada atención de salud. Teniendo en cuenta la limitada información disponible sobre el uso de la sangre y sus componentes en América Latina y el Caribe, el Grupo Cooperativo Iberoamericano de Medicina Transfusional (GCIAMT), mediante sus comités de Investigación y de Asuntos Internacionales, llevó a cabo un proyecto de elaboración de un protocolo que facilitara la evaluación del uso de la sangre a nivel de país, jurisdiccional e institucional, en diversos contextos de país. Expertos en seguridad de la sangre de la Organización Panamericana de la Salud (Washington, DC, Estados Unidos), la Universidad de São Paulo (São Paulo, Brasil), el Hemocentro de São Paulo (São Paulo, Brasil) y el GCIAMT diseñaron un protocolo integral de evaluación del uso de la sangre en 2 etapas: en la primera se recopilan datos de las solicitudes de sangre, y en la segunda, de las historias clínicas. Como mínimo, es preciso analizar 1 000 solicitudes; por ello, los períodos de estudio varían en dependencia del número de solicitudes de transfusión expedidas. Una aplicación basada en internet, el Modular Research System, Study Management System, alberga los datos y elabora informes sobre cómo solicitan sangre los hospitales, cómo se expide la sangre, quién requiere sangre y componentes sanguíneos y, como beneficio añadido, cuántas unidades de sangre se desperdician y cuál es la demanda real de sangre.

[External performance evaluation of screening in blood banks in Argentina: results and strategies for improvement]. / Evaluación externa del desempeño en el tamizaje de bancos de sangre en Argentina: resultados y estrategias para mejorarlo.

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.

Cyclophosphamide effect on coccidioidomycosis in the rat

El proposito de este trabajo fue estudiar el efecto de la inmunosupresión causada por la droga ciclofosfamida (CY) sobre la infección de la rata con Coccidioides immitis por via intracarrata por vía intracardíaca. Este huésped fue empleado como modelo experimetnal, ya que presenta una evolución de la enfermedad semejante a la del hombre, alcanzando una etapa crónica con granulomas principalmente restringidos a los pulmones. Se utilizaron três esquemas de CY: A) 4 dosis de 20 mg/Kg cada uma, antes de la inoculación de Ci; B) 4 dosis de igual cantidad de CY, luego de la infección; y C) 6 dosis de 20 mg/Kg cada una, administradas desde el día + 1 hasta + 4 y continuando los dias + 8 + 9 post-infección (pi). Los dos primeros esquemas inhibieron la formación de anticuerpos hasta el día 28 pi, sin modificar la respuesta celular a la coccidioidina, medida como hinchazón de la almohadilla plantar. Se observó una mayor diseminación fúngica inicial, autolimitándose más tarde. Por el contrário, el esquema C provocó un 55% de mortalidad, disminución de la respuesta humoral y celular, acompañada de una extensa diseminación del Ci. La histología mostró alteraciones significativas, tales como persistencia de esporangios de primoinfección, correspondientes al estadío agudo de la coccidioidomicosis, con ausencia de desarrollo de granulomas. Por lo tanto, la depresión observada en la respuesta celular debido al tratamiento con CY sería la responsable de la ausencia de la reacción inflamatória capaz de restringir la proliferación de esporangios en los tejidos, lo cual a su vez favorece la diseminación del microorganismo patógeno y el aumento de mortalidad

Experimental coccidioidomycosis in the immunosuppressed rat

C. immitis inoculated rats are known to develop infection restricted to lung whereas cyclophosphamide (CY) treatment leads to widespread dissemination with considerable mortality. In this study, an attempt was made to elucidate the mechanisms involved in such behaviour. With this aim, spleen cells were transferred from infected CY-treated to infected untreated rats, achieving significant specific inhibition in footpad swelling to coccidioidin in recipients, attributable to a suppressor T cell subpopulation induced by greater fungal antigen concentration arising from widespread C. immitis dissemination in immunosuppressed animals. NK activity proved similar regardless of CY treatment. Lastly, chronically infected rats presented increased colony forming units count after several weekly doses of CY, as happens in immunosuppressed patients harbouring a previous infection

Evaluación externa del desempeño en el tamizaje de bancos de sangre en Argentina: resultados y estrategias para mejorarlo / External performance evaluation of screening in blood banks in Argentina: results and strategies for improvement

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 por ciento), 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

Inmonopatología inducida en la rata por virus Junín / Immunopathology induced in the rat by Junin virus

La infección de la rata de 10 días de vida por vía intracerebral con la cepa XJ del virus Junín, da lugar a un cuadro encefalítico con un 100% de mortalidad. Los presentes experimentos con suero antitimocito (SAT) demuestran la participación de la respuesta celular en la patología de este grupo etario. En cuanto al tratmiento con SAT, se utilizaron tres esquemas, siendo el más efectivo el que consistió en dosis desde el día -1 hasta el día +9, y en los días +12, +14 y +16, siendo el día 0 el de la inoculación de virus. Se alcanzó un 54% de sobrevida y un retraso en el día promedio de muerte de 12 días. No hubo diferencias en el título en cerebro de los animales tratados y los controles infectados. Las ratas de 2 días de vida al recibir el virus presentan persistencia. Cuando a estos animales se les transfirieron esplenocitos de ratas infectadas a los 10 días de edad se produjo una mortalidad de 40% en los receptores. Por lo tanto puede concluirse que: a) la encefalitis en el animal de 10 días de vida es de origen inmunológico y b) la rata de 10 días presenta una población linfocitaria que al ser transferida al animal persistente, provoca enfermedad y muerte

Protección contra la encefalitis producida en ratas por una cepa patógena de virus Junín por inoculación periférica con una cepa atenuada / Protection against encephalitis in rats caused by a pathogenic strain of the Junin virus, using peripheral inoculation of an attenuated strain

La rata recién nacida infectada con la cepa atenuada XJC13 del virus Junín por vía ip, no desarrolla enfermedad, mientras que los animales inoculados ic a los 8-12 días de vida con la cepa prototipo XJ presentan un 100% de mortalidad con signos neurológicos. El objetivo de este estudio fue lograr una protección en este modelo neurológico y tratar de determinar los mecanismos involucrados en la misma. El mayor porcentaje de sobrevida 75%, se obtuvo cuando a ratas recién nacidas se les administró la cepa XJC13 por vía ip y a los 12 días de edad se les desafió con la cepa XJ por vía ic. Para determinar los mecanismos involucrados en la protección se estudió en los animales protegidos: a) Título de virus en cerebro: fue de 3 log menos que los controle infectados solamente con XJ. Las ratas que recibieron sólo XJC13 presentaron bajos títulos. b) Título de anticuerpos neutralizantes: no fueron diferentes entre ambos grupos, lo que indica que no habría un efecto de respuesta secundaria en los animales protegidos. c) La administración de suero de ratas inoculadas con XJC13 y obtenido 10 días más tarde o de interferón alfa endógeno o oxógeno, no alteraron la mortalidad de animales que fueron infectados ic con XJ a los 12 días de vida. d) La transferencia de esplenocitos de ratas infectadas con la cepa atenuada 10 días antes, protegió contra el desafío con XJ, disminuyendo la mortalidad en un 55% con respecto al grupo control. Tratando los esplenocitos con suero antimocito más complement ...