Marcia M. Otani

WHO comparative evaluation of serologic assays for Chagas disease

BACKGROUND: Evaluation of commercially available test kits for Chagas disease for use in blood bank screening is difficult due to a lack of large and well‐characterized specimen panels. This study presents a collaborative effort of Latin American blood centers and the World Health Organization (WHO) to establish such a panel.

Descarte de bolsas de sangue e prevalência de doenças infecciosas em doadores de sangue da Fundação Pró-Sangue/Hemocentro de São Paulo

OBJETIVO: Analisar a evolucao, de 1991 a 2001, do descarte sorologico na Fundacao Pro-Sangue/Hemocentro de Sao Paulo, o maior banco de sangue da America Latina, e verificar a prevalencia de doencas infecciosas entre doadores dessa instituicao no ano de 2001. METODOS: Foram compilados os dados de descarte sorologico relativos aos anos de 1991 a 2001. Para determinar a prevalencia de doencas infecciosas, foram analisadas 9 942 amostras triadas em novembro de 2001, sendo as amostras reativas submetidas a testes confirmatorios. RESULTADOS: Foi encontrada uma diminuicao percentual significativa de descarte, de 20% em 1991 para 9% em 2001. A prevalencia de doencas infecciosas entre doadores em 2001 foi de 0,04% para virus da imunodeficiencia humana (VIH); 0,21% para virus da hepatite C (VHC); 0,06% para virus T-linfotropico humano (HTLV); para virus da hepatite B (VHB), as prevalencias foram de 0,14% para anti-HBc + HBsAg, 1,68% para anti-HBc + anti-HBs e 1,67% para anti-HBc isolado; 1,10% para sifilis; e 0,14% para doenca de Chagas. CONCLUSAO: A diminuicao no descarte e a prevalencia de doencas infecciosas entre doadores da Fundacao Pro-Sangue/Hemocentro de Sao Paulo em 2001 refletem o aumento na porcentagem de doadores de repeticao nesse banco de sangue.

Evaluation of the Performance of Brazilian Blood Banks in Testing for Chagas’ Disease

Background and Objectives: Due to the low sensitivity and reproducibility of available tests, in 1989 it became mandatory for all Brazilian blood donors to be screened for Chagas’ disease by at least two serological techniques. In 1994 the Brazilian Ministry of health launched a program to systematically evaluate the quality of serological screening for the detection of blood-transmissible diseases as performed by public blood banks. Methods: A blind panel containing positive samples for blood-transmissible disease was distributed to 57 major public blood banks in four sequential programs. Results: The ELISA test was chosen by the majority of the blood banks. There were 64 (3.7%) false-negative results, 49 produced by banks using indirect hemagglutination. Since most blood banks screened with more than one test for Chagas, only 8 samples were actually missed, of which 3 were by banks using only one test. Conclusion: Our data show a clear improvement in performance of Brazilian blood banks testing for Chagas’ disease.

Antibody levels correlate with detection of Trypanosoma cruzi DNA by sensitive polymerase chain reaction assays in seropositive blood donors and possible resolution of infection over time

BACKGROUND: The clinical significance of anti‐Trypanosoma cruzi low‐level reactive samples is incompletely understood. Polymerase chain reaction (PCR)‐positive rates and antibody levels among seropositive blood donors in three countries are described.

Consequences of Nucleic Acid Amplification Testing for Blood Transfusion Centres

This article is also accessible online at: http://BioMedNet.com/karger Blood banks and transfusion centres are faced with the imminent introduction of nucleic acid amplification testing (NAT), or genomic amplification testing of plasma pools used by the plasma industry. The Committee for Proprietary Medicinal Products (CPMP) in Europe requires that all manufactured plasma pools should be tested for HCV RNA by NAT by July 1, 1999. To avoid the destruction of large NAT-reactive plasma pools, the CPMP strongly advises to implement a system for the screening of minipools of plasma by NAT. In future, genomic screening of individual donations for blood-borne viruses is expected to become obligatory. At present, genomic screening of individual donations cannot be routinely performed, and NAT minipool screening (i.e. a pool of plasma of 100 donations) is not (well) standardized, is costly and time-consuming, especially when the individual positive donors from a positive pool have to be sorted out. An especially difficult and ethical question is what should be decided concerning the release of red cell products and especially platelets when minipool screening is implemented. Either these cellular products will be blocked for at least several days, creating shortage and loss of product, or the results of minipool screening tests will not affect these products. This may create different levels of safety and serious ethical problems by informing (or not informing) recipients of these products after a positive result has been obtained. Fourteen experts in the field were asked for their opinion, answers were obtained from 10 of them on the following questions.

Programas de control externo de la calidad en serología desarrollados en América Latina con el apoyo de la OPS entre 1997 y 2000

OBJETIVOS: Con el apoyo de la Organizacion Panamericana de la Salud (OPS), desarrollamos entre 1997 y 2000 cinco programas de control externo de la calidad en serologia (PCECS) en los que participaron entre 13 y 21 bancos de sangre de 11 a 16 paises de America Latina. El objetivo fue evaluar el desempeno de los bancos de sangre con respecto al tamizaje serologico realizado en donantes de sangre. METODOS: Como herramienta de trabajo utilizamos conjuntos de 24 muestras de sueros anonimos con reactividades variables para los parametros de uso obligatorio en el tamizaje serologico de donantes de sangre en Brasil. En cada PCECS enviamos un multipanel a cada institucion participante para que lo procesara en las mismas condiciones de su rutina de tamizaje. Cada participante recibio la clave del multipanel para autoevaluacion, despues de haber devuelto los resultados obtenidos en su laboratorio. Se mantuvo siempre la mas estricta confidencialidad sobre los resultados obtenidos individualmente. Al terminar de cada programa, el Centro Organizador (Superintendencia de Serologia de la Fundacao Pro-Sangue/Hemocentro de Sao Paulo) elaboro un informe final que contenia toda la informacion obtenida en el programa y que fue enviado a los participantes. RESULTADOS: En el analisis de los cinco PCECS se observo falta de homogeneidad entre los paises con respecto a las estrategias y a los parametros utilizados en el tamizaje de donantes de sangre. Pocos laboratorios practicaron el tamizaje de los virus linfotropico de celulas T humanas (HTLV) (17%, 27%, 35%, 39% y 45%, respectivamente y en orden creciente para los cinco PCECS) y de anticuerpos contra el antigeno nuclear del virus de la hepatitis B (anti-HBc) (42%, 27%, 39%, 50% y 60%). Tambien 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 numero total de resultados positivos falsos oscilo 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 America Latina para reforzar los procedimientos de tamizaje serologico en bancos de sangre, incluso los PCECS, hasta que se consiga una uniformidad de procedimientos en la Region de las Americas.

Evaluation of the concomitant use of two different EIA tests for HIV screening in blood banks

OBJECTIVE In 1998, the Brazilian Ministry of Health made it mandatory for all blood banks in the country to screen donated blood for human immunodeficiency virus (HIV) concomitantly using two different enzyme immunoassay (EIA) tests. Concerned with the best use of available resources, our objective with this study was to evaluate the usefulness of conducting two EIA screening tests instead of just one. METHODS We analyzed data from 1999 through 2001 obtained by testing 698 191 units of donated blood using two EIA HIV screening tests concomitantly at the Pro-Blood Foundation/Blood Center of São Paulo (Fundação Pró-Sangue/Hemocentro de São Paulo), which is a major blood center in the city of São Paulo, Brazil. All samples reactive in at least one of the two EIA tests were submitted for confirmation by a Western blot (WB) test, and the persons who had donated those samples were also asked to return and provide a follow-up sample. RESULTS Out of the 698 191 blood units that were donated, 2 718 of them (0.4%) had to be discarded because they were reactive to at least one of the EIA tests. There were two WB-positive donation samples that were reactive in only one HIV EIA screening test. On their follow-up samples, both donors tested WB-negative. These cases were considered false positive results at screening. Of the 2 718 donors who were asked to return and provide a follow-up sample, 1 576 of them (58%) did so. From these 1 576 persons, we found that there were two individuals who had been reactive to only one of the two EIA screening tests and who had also been negative on the WB at screening but who were fully seroconverted on the follow-up sample. We thus estimated that, in comparison to the use of a single EIA screening test, the use of two EIA screening tests would detect only one extra sample out of 410 700 units of blood. CONCLUSIONS Our data do not support the use of two different, concomitant EIA screening tests for HIV. The great majority of HIV-positive donors have already seroconverted and will be detected using only a single EIA screening test. Only persons who are going through the process of seroconversion may be missed by using a single EIA test and detected using two EIAs for screening. To screen out these individuals and decrease the residual risk of HIV transmission from the blood donated in our center, the use of other techniques, such as nucleic acid testing (NAT) or a p24 antigen assay, would be more effective.

Antibody levels correlate with detection ofTrypanosoma cruziDNA by sensitive polymerase chain reaction assays in seropositive blood donors and possible resolution of infection over time: T. CRUZIANTIBODY LEVELS AND PCR STATUS

BACKGROUND: The clinical significance of anti‐Trypanosoma cruzi low‐level reactive samples is incompletely understood. Polymerase chain reaction (PCR)‐positive rates and antibody levels among seropositive blood donors in three countries are described.

Antibody levels correlate with detection of Trypanosoma cruzi DNA by sensitive PCR assays in seropositive blood donors and possible resolution of infection over time

BACKGROUND: The clinical significance of anti‐Trypanosoma cruzi low‐level reactive samples is incompletely understood. Polymerase chain reaction (PCR)‐positive rates and antibody levels among seropositive blood donors in three countries are described.

Re: “WHO evaluation of the serologic assays for Chagas disease”

to the rheology and to the adverse effects in patients as observed by Koch and coworkers. The results of the current rheologic studies and the survival studies can be considered complementary to each other, rather than contradictory. It suggests that not the altered rheology, nor membrane receptor expression (both would apply more or less to the whole population), but release products, such as iron or cytokines, contribute to the clinically adverse effects. These release products may even exist in part in the transfusion bag. If this can be proven it may result in effective measures, such as cell wash or antioxidant strategies. The implications of these observations also reach to the use of autotransfusion of suctioned blood during (heart) operation procedures, as discussed by Adamson. Even when the overall quality of these suctioned RBCs is good, it may contain a fraction of damaged or removalprone RBCs, which has clinical adverse effects in patients after transfusion. Since the quantity of suctioned blood during cardiopulmonary bypass procedures is substantial, a combined effect of older banked blood and suctioned blood is conceivable.