ABSTRACT
【Objective】 To evaluate the effectiveness of random quality control sampling in blood sample detetion by ELISA. 【Methods】 Blood samples of 5 mL specification of blood donors from our blood station from May to July 2022 were selected for routine operation on a fully automated sampler. J standard substances(3 mL specification) as daily samples were added to A1 well, H12 well and random wells of HBsAg, anti-HCV, anti-HIV, and -TP, and then placed in a fully automated enzyme immunoassay analyzer for testing. With random well quality control as the internal quality control judgment standard, 20 consecutive tests were conducted and were divided into A1 (well) group, H12 (well) group and random (well) group according to different well positions. Quality control maps were drawn using Levey-Jennings quality control chart with random group as the framework, and were compared with the quality control map of A1 well and H12 well results in the same day. 【Results】 The mean quality control levels of infectious indicators of blood transfusion in blood donors by ELISA were: HBsAg 3.87±0.28, anti-HCV 3.79±0.38, anti-HIV 3.64±0.30 and anti-TP 4.53±0.51. 【Comparison】 of HBsAg, anti-HCV, anti-HIV and anti-TP, between random group, A1 group and H12 group were HBsAg 3.87± 0.28 vs 4.09±0.30 vs 3.64±0.26, anti-HCV 3.78±0.37 vs 3.96±0.38 vs 3.63±0.38, anti-HIV 3.63±0.31 vs 3.82±0.32 vs 3.48±0.28 and anti-TP 4.51±0.51 vs 4.71±0.52 vs 4.36±0.51, The S/CO value of each indicator were H12 group<random group<Al group (P<0.05), and the mean quality control levels of random group were similar to each detection indicator (P>0.05) . Using random group as the quality control framework standard, 5 points in group A1 fell outside of +2s, and 1 point in group H12 fell outside of -2s, resulting in a total of 6 alarms. With the quality control substance placed in A1 well of the ELISA plate, the judgment of detection results of the entire ELISA plate could be inevitably affected, especially the last row of low concentration virus marker samples on the ELISA plate. 【Conclusion】 The application of random quality control sampling method in donor blood by ELISA is scientific and reasonable, which can reduce the systematic error caused by artificial setting of ELISA plate fixed well positions and can also discover edge effects that affect the detection results.
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【Objective】 To improve the efficiency and screening strategy by evaluating the performance of HBsAg screening before blood donation in Dalian. 【Methods】 The confirmed HBsAg positive samples were detected qualitatively and quantitatively, and retested with HBsAg rapid testing kit pre-donational used parallelly. Efficiency of HBsAg screening before donation was calculated, and compared between first-time and repeated donors. 【Results】 The pre-donation HBsAg screening was conducted for 199 553 cases, including 95 321 first-time donors (63.2%) and 55 396 repeated donors(36.8%).1 015 donors (first-time/repeated: 999/16) were reactive in HBsAg rapid testing. 113 samples (first-time/repeated: 108/5), initially negative in HBsAg rapid testing, were confirmed HBsAg positive by laboratory testing. The efficiency of pre-donation HBsAg screening for first-time donors(10.9‰) was significantly higher than that of repeated donors(0.3‰)(P130) and 92.44 (18.7->130), respectively. 【Conclusion】 The HBsAg rapid testing kit used in Dalian Blood Center could meet requirements for blood donor screening before donation, while good efficiency of HBsAg pre-donation screening could be achieved only in first-time blood donors.
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Background & objectives: Nucleic acid amplification test (NAT) in blood donor screening not only detects window period (WP) donors but also those with chronic occult infections which are negative by routine serological screening. This study was conducted to determine the time trend of NAT positivity and seroprevalence of transfusion-transmitted infections (TTIs) through a period of six years and evaluate the strength of NAT as a supplementary test in identifying the cryptic carriers in blood donor population. Methods: A total of 1,01,411 blood donations were screened between January 2011 and December 2016 by the ELISA and individual donor (ID) NAT Procleix Ultrio Plus Assay. Additional molecular and serological assays were done on the NAT yield samples to differentiate the type of cryptic carriers. Results: NAT yields comprised 0.05 per cent (50/101411) of the total samples tested with a yield rate of 1/2028. Hepatitis B virus (HBV) contributed to 80 per cent of the total NAT yields and the rest 20 per cent due to hepatitis C virus (HCV). Majority of HBV NAT yields (75%) were from chronic occult donors and 25 per cent were WP donors. Both HBV and HCV NAT yields had a wide range of viral count. There was no HIV NAT yield. A significant decline in the prevalence rate of TTIs through the study period of six years was observed. Interpretation & conclusions: The cryptic infections found in blood donors increase the risk of TTIs. Blood screening by both serology and NAT can reduce this threat.
ABSTRACT
INTRODUCTION: Blood transfusion is an important transmission route of Trypanosoma cruzi (T cruzi), a major parasitic infection in Central and South America. The limited treatment options are most effective in acute Chagas' infection. At present, there is no current data on the prevalence of T cruzi in the blood donor population of Guyana. This information is necessary to protect the supply of the blood donation programme. This study sought to determine the prevalence of T cruzi in the blood supply at the National Blood Transfusion Services of Guyana with the hope of providing knowledge to the on-going surveillance for Chagas' disease worldwide and therefore address the risk of its spread by blood transfusion. METHODS: Two commercialized ELISAs utilizing crude or recombinant T cruzi antigens were used to study 2000 blood samples voluntarily donated for the purpose of altruistic or family replacement donation retrospectively. RESULTS: The results showed that approximately 1 in 286 donations tested positive for antibodies to T cruzi. CONCLUSION: These results indicate that T cruzi continues to be a risk in Guyana and there is a need to continue screening donated blood. Trypanosoma cruzi is a life-long infection and infected persons may be asymptomatic chronic carriers of the disease. Education, housing improvement, and controlled use of insecticides should be introduced to contain Chagas' disease.
INTRODUCCIÓN: La transfusión de Sangre es una vía de transmisión importante del Trypanosoma cruzi (T cruzi), una infección parasitaria mayor en América Central y América del Sur. Las opciones de tratamiento limitadas son más eficaces en los casos de la enfermedad de Chagas aguda. En el presente, no existen datos actualizados acerca de la prevalencia del T cruzi en la población de donantes de sangre en Guyana. Esta información es necesaria para proteger el suministro del programa de donación de sangre. Este estudio se propuso determinar la prevalencia de T cruzi en el suministro de sangre de los Servicios Nacionales de Transfusión de Sangre en Guyana, con la esperanza de aportar conocimientos a la vigilancia que tiene lugar en relación con la enfermedad de Chagas a nivel mundial, y por consiguiente aborda el riesgo de la difusión de esta última mediante la transfusión de sangre. MÉTODOS: Dos inmunoensayos ELISA con antígenos de T cruzi crudos o recombinantes, fueron utilizados a fin de estudiar 2000 muestras de sangre donadas voluntariamente a modo de donaciones altruistas o de reposición familiar, retrospectivamente. RESULTADOS: Los resultados mostraron que aproximadamente 1 de 286 donaciones daban positivo a anticuerpos frente al T cruzi. CONCLUSIÓN: Estos resultados indican que el T cruzi sigue siendo un riesgo en Guyana, y hay necesidad de continuar tamizando la sangre donada. El Trypanosoma cruzi es una infección crónica, y las personas infectadas pueden ser portadores asintomáticos crónicos de la enfermedad. Deben introducirse medidas en cuanto a educación, mejoramiento de las viviendas, y uso controlado de insecticidas, a fin de detener la enfermedad de Chagas.
Subject(s)
Humans , Antibodies, Protozoan/blood , Blood Safety , Chagas Disease/epidemiology , Chagas Disease/immunology , Trypanosoma cruzi/immunology , Guyana/epidemiology , Prevalence , Seroepidemiologic StudiesABSTRACT
Background & objectives: Safe blood and blood products should be offered to all patients in need for blood transfusion. The objectives of the present study were to establish prevalence estimates for hepatitis B and hepatitis C virus infections as a foundation for safe blood transfusion in rural Vietnam, and to check the accuracy of the laboratory analysis used for hepatitis testing of blood donors in Vietnam. Methods: A cross-sectional study was conducted in two rural communities in Quang Tri, Vietnam. A total of 1,200 blood samples collected from potential blood donors were tested by an enzyme immunoassay technique (EIA) for detection of hepatitis surface antigen (HBsAg), antibodies to hepatitis B core antigen (anti-HBc), and antibodies to hepatitis C antigen (anti-HCV). The EIA test outcome was validated by a chemiluminescent micro particle immunoassay technique (CMIA). Results: The prevalence of HBsAg and anti-HBc in the study population was 11.4 per cent (95% CI 9.6 - 13.2) and 51.7 per cent (95% CI 48.8 - 54.5), respectively, the prevalences being higher in males than females. The prevalence of anti-HCV was 0.17 per cent. The test agreement between the EIA and CMIA techniques was high both for HBsAg detection (κ = 0.91; 95% CI: 0.83 - 0.99) and for anti-HBc detection (κ = 0.89; 95% CI 0.81 - 0.97). Compared to CMIA results, the positive and negative predictive values of the EIA tests were found to be 94.9 per cent (95% CI 87.5 - 98.6) and 97.5 per cent (95% CI 86.8 - 99.9) for HBsAg, and 92.4 per cent (95% CI 84.2 - 97.2) and 100 per cent (95% CI 91.2 - 100) for anti-HBc. Interpretation & conclusions: The study shows that hepatitis B virus infection is endemic in rural areas of Vietnam and that almost half of the population is or has been infected. Hepatitis C infection is rare, but false negative test results cannot be ruled out. Also, the results indicate that the EIA performance in blood donor screening in Vietnam may be sub-optimal, missing 2.5 per cent of hepatitis B virus carriers and falsely excluding more than 7 per cent of blood donors. As the prevalence of hepatitis B infection is high, occult hepatitis B infection may represent a threat to safe blood transfusion. Therefore, nucleic acid amplification testing for HBV should be considered for blood donor screening in Vietnam.
ABSTRACT
Classical serological screening assays for Chagas' disease are time consuming and subjective. The objective of the present work is to evaluate the enzyme immuno-assay (ELISA) methodology and to propose an algorithm for blood banks to be applied to Chagas' disease. Seven thousand, nine hundred and ninety nine blood donor samples were screened by both reverse passive hemagglutination (RPHA) and indirect immunofluorescence assay (IFA). Samples reactive on RPHA and/or IFA were submitted to supplementary RPHA, IFA and complement fixation (CFA) tests. This strategy allowed us to create a panel of 60 samples to evaluate the ELISA methodology from 3 different manufacturers. The sensitivity of the screening by IFA and the 3 different ELISA's was 100%. The specificity was better on ELISA methodology. For Chagas disease, ELISA seems to be the best test for blood donor screening, because it showed high sensitivity and specificity, it is not subjective and can be automated. Therefore, it was possible to propose an algorithm to screen samples and confirm donor results at the blood bank.
Os testes sorológicos clássicos utilizados na triagem de doadores de sangue são trabalhosos e subjetivos. O objetivo do presente trabalho é o de avaliar a metodologia imuno-enzimática (ELISA) e propor um algorítmo para doença de Chagas em bancos de sangue. Foram estudados 7999 doadores de sangue e/ou componentes cujas amostras foram testadas com o objetivo de tria-las sorologicamente para doença de Chagas utilizando hemaglutinação passiva reversa (RPHA) e imunofluorescência indireta (IFA). As amostras reativas em pelo menos uma destas metodologias, foram retestadas com reativos diferentes por RPHA, IFA e fixação de complemento (CFA). Esta estratégia nos permitiu criar um painel de 60 amostras com as quais tornou-se possível a avaliação do método imunoenzimático (ELISA). A sensibilidade da triagem dos doadores pelos métodos ELISA e IFA foi de 100%. A especificidade foi melhor para a metodologia imunoenzimática. O teste ELISA parece ser o ideal para triagem em bancos de sangue pois é altamente sensível, específico, não é subjetivo e pode ser automatizado. Desta forma, torna-se possível a formulação de um algorítimo a ser utilizado na triagem sorológica e confirmação de resultados em doadores de bancos de sangue.