The efficacy of a malarial antibody enzyme immunoassay for establishing the reinstatement status of blood donors potentially exposed to malaria

BACKGROUND AND OBJECTIVES: The two key objectives of the study were, first, to evaluate the sensitivity and specificity of a recombinant antigen-based malarial enzyme-linked immunoassay (EIA) and, second, to estimate the risk associated with implementing this test with a shortened cellular component restriction period (6 months rather than the standard 12-36 months) for blood donors with a malarial risk exposure. MATERIALS AND METHODS: Blood donors were recruited into four distinct groups [non-exposed (control), malarial area 'visitors', 'residents' and 'previous infection') and screened by using the Newmarket malarial antibody EIA. Assay specificity was evaluated in unexposed blood donors, and sensitivity was determined in acute clinical samples. RESULTS: No parasitaemic donors were detected amongst 337 malarial 'visitors' who had returned from a malaria-endemic area less than 6 months previously, or for 402 'visitors' or 'residents' who had returned from a malaria-endemic area more than 6 months previously. The incidence of malarial antibodies within the exposed blood donor groups was 1.33% (10/751). In acute clinical non-donor samples, the Newmarket EIA detected 106/108 (98.1; 93.5-99.5%) 'film' positive Plasmodium falciparum infections and 12/12 (100, 75.7-100.0%) P. vivax infections. The estimated additional risk exposure of the proposed new strategy was one infectious P. falciparum donation per 175 years or 1 per 4.2 years for P. vivax. CONCLUSIONS: The study findings support the efficacy and safety of a targeted screening strategy combining antibody screening with a 6-month cellular component restriction period for donors with a declared malarial risk.     

Multicentric evaluation of the DiaMed enzyme-linked immunosorbent assay malaria antibody test for screening of blood donors for malaria

BACKGROUND: The risk of malaria transmission by blood transfusion is critical due to extensive travel from endemic areas to non-endemic areas. An enzyme-linked immunosorbent assay (ELISA) malaria antibody test has been developed that is claimed to perform better than the immunofluorescence assay test (IFAT). The assay contains antigens to both Plasmodium falciparum and Plasmodium vivax. A multicentre study was performed to evaluate the appropriateness of replacing the IFAT by the new ELISA test. MATERIAL AND METHODS: Nine French blood banks participated in this multicentre study. Two panels of samples were evaluated. The first included 4163 samples from healthy donors and was used to calculate clinical specificity of the assay. The second involved 10,995 samples, either collected retrospectively or prospectively from malaria-risk donors , was used to assess the comparative performance of the ELISA and IFAT. Discordant samples were further tested using an in-house IFAT and also tested for presence of Plasmodium DNA by polymerase chain reaction. RESULTS: The ELISA showed a clinical specificity of 99.02%. In the malaria-risk blood donors groups, the retrospective group showed a concordance rate of 92.6% (k = 0.90), while the prospective group showed a concordance rate of 97% (k = 0.46). After confirming the discordant sample results by an in-house IFAT, the k index increased to 0.81. None of the discordant samples was shown to contain Plasmodium DNA. CONCLUSION: The performance of the ELISA test in this study has confirmed its potential as a new screening test for use in blood banks, as an alternative to the IFAT in prevention of transfusion-transmitted malaria in non-endemic countries.     

Recent experience with human immunodeficiency virus transmission by cellular blood products in Germany: antibody screening is not sufficient to prevent transmission

BACKGROUND AND OBJECTIVES: A case of transfusion-related human immunodeficiency virus-1 (HIV-1) transmission was not detected by standard HIV antibody screening. MATERIALS AND METHODS: In a look-back procedure, the preceding donations were extensively analyzed by nucleic acid amplification technology (NAT) screening and alternative serological tests. RESULTS: The chain of infection could be demonstrated by the analysis of HIV-specific amplicon sequences from the donor and the recipient. CONCLUSION: This case report clearly indicates that the remaining risk of transfusion-related transmission of HIV could be severely reduced, not only by the use of NAT screening but even by HIV antigen screening or more sensitive HIV antibody assays.     

Evaluation of the utility of the HemoCue 301 haemoglobinometer for blood donor screening

BACKGROUND AND OBJECTIVES: Reliable blood donor screening requires more accurate measure of haemoglobin (Hb) than by either copper sulphate or the haemoglobin colour scale. The HemoCue haemoglobinometer has established a method for this, but it is considerably more expensive; a modified version (HemoCue 301) has now been developed with a cheaper reagent-free cuvette for use in budget-restricted situations. This report describes evaluation of the performance, the assessment of reproducibility and accuracy of this modified analyser against the reference technique for Hb measurement. MATERIALS AND METHODS: Over 300 routine blood samples from specimens received routinely in a hospital laboratory were tested in accordance with the International Committee for Standardization in Haematology (ICSH) protocol. Accuracy and linearity were confirmed by the reference method with the WHO international haemoglobincyanide reference standard. Tests were also performed on selected samples for checking interference by biochemical abnormalities and leucocytosis. The effects of various sample storage conditions prior to testing were also tested. RESULTS: Ninety per cent of results were within 4% of true values, 96% within 6% and in only three cases was the deviation > 10%, due to interference by bilirubinaemia and/or C-reactive protein. At an Hb value of 120 g/l for donor selection, there were no cases where the method would have been misleading. CONCLUSION: HemoCue 301 provides a simple and reliable anaemia screen method, conforming to the requirements of CLIA'88 regulations; it is reliable for discriminating Hb values for donor acceptance. The main advantage is that the cuvettes are significantly cheaper than the previous models, and will not deteriorate in adverse climatic conditions.     

Evaluation of capillary haemoglobin determination for anaemia screening in blood donation settings

BackgroundAn accurate assessment of hemoglobin (Hb) values before donation is unavoidable for safeguarding donors’ safety and fulfilling the current specifications of Hb content in blood bags. This study was hence aimed to compare a finger-prick method for Hb measurement in capillary blood with Hb assessment in venous blood using a hematological analyser.ResultsA significant overestimation was found with HemoCue compared to UniCel DxH800, but the correlation between methods was significant (comprised between 0.600 and 0.759; all p<0.01) and the bias always lower than the quality specifications. The prevalence of Hb values below the gender-specific thresholds for blood donation was also not significantly different (p=0.186).DiscussionIt can hence be concluded that the finger-prick method evaluated is a safe and reliable means for screening blood donors.     

微柱凝胶法检测Rh血型免疫性抗体的分析

目的：探讨Rh血型免疫性抗体筛查及特异性鉴定在临床输血和新生儿溶血病预防中的意义,观察微柱凝胶法检测Rh血型免疫性抗体的敏感性。方法：应用微柱凝胶法对患者输血前和孕妇产前做Rh血型免疫性抗体筛查,对筛查阳性者进一步做抗体特异性鉴定及效价测定。结果：在9878例患者中检出Rh血型免疫性抗体阳性86例（0.87%）,其中抗D12例（14.0%）,抗E25例（29.1%）,抗C11例（12.8%）,抗c9例（10.5%）,抗e4例（4.7%）,抗Ce7例（8.1%）,抗CE5例（5.8%）,抗CD6例（6.9%）,抗cD3例（3.5%）,抗cE4例（4.7%）。结论：在输血前和产前对拟输血患者和夫妇血型不合的孕妇进行Rh血型免疫性抗体筛查、特异性鉴定及效价测定,对确保输血安全及优生优育有重要的临床意义。     

Screening of living organ donors for endemic infections: Understanding the challenges and benefits of enhanced screening

Living organ donor candidates are screened for medical and psychosocial contraindications to donation. One important goal of this process is to prevent donor‐derived infectious diseases transmissions. These transmissions are exceptionally rare, but have the potential to cause significant morbidity and mortality. The Organ Procurement and Transplantation Network now requires each recovery hospital to develop a protocol for evaluating living donors for tuberculosis and other geographically defined endemic pathogens, including Trypanosoma cruzi (the causative pathogen of Chagas’ disease), Strongyloides stercoralis, and West Nile Virus (WNV), in addition to universal screening for blood‐borne pathogens. Enhanced screening requirements were developed in response to the changing epidemiology and endemicity of these diseases, as well as recent case reports of donor‐derived disease transmission. Living organ donor disease screening presents a number of unique challenges to clinicians and policy‐makers, including deciding which donors to test, which testing modality to use, when to test, and appropriate interpretation of results. This review will analyze the epidemiology of T. cruzi, S. stercoralis, and WNV, the assays available for screening for these diseases, and the subsequent impact on the living organ donor process.     

Guidelines for microplate techniques in liquid-phase blood grouping and antibody screening

Summary. This document is an introduction to microplate serology prepared at a time of very active research and development. Antibody detection techniques are expected to improve during the lifetime of this document. Approximately 25% of hospital blood banks are ABO and D grouping by microplate techniques. Antibody screening by microplate techniques is only being carried out by a small percentage of hospital blood banks but there is likely to be a change to antiglobulin tests by microplate procedures as soon as the methods have been thoroughly tested and approved. There are one or two weak links in these procedures which could give rise to serious errors:— (1) Antiglobulin reagents standardized for spin-tube tests may be subject to prozones in liquid phase microplate tests. Each new batch of antiglobulin reagent must be standardized by the microplate procedure in use to show that the reagent is at its optimum anti-IgG dilution for use. However dilutions greater than 1:2 may seriously compromise the anti-complement activity of the reagent. (2) Automated cell washers for microplates are currently under development and should be evaluated by replicate tests with weak anti-D sensitized cells. (3) The combination of diluted anti-IgG and poor washing procedures may lead to neutralization of anti-IgG and cause false negative errors. Future development for improved antiglobulin tests in microplates by a solid phase system is now well advanced and workers proposing to change to antibody screening by microplates are advised to bear this in mind. It is hoped that microplate methodology will move towards standardization based on national guidelines using standard antibody reagents for the validation of new microplate procedures.     

Malaria antibody persistence correlates with duration of exposure

Background and Objectives In Australia, the risk of transfusion‐transmitted malaria is managed through the identification of ‘at‐risk’ donors, antibody screening enzyme‐linked immunoassay (EIA) and, if reactive, exclusion from fresh blood component manufacture. Donor management depends on the duration of exposure in malarious regions (>6 months: ‘Resident’, <6 months: ‘Visitor’) or a history of malaria diagnosis. We analysed antibody testing and demographic data to investigate antibody persistence dynamics. To assess the yield from retesting 3 years after an initial EIA reactive result, we estimated the proportion of donors who would become non‐reactive over this period. Materials and Methods Test results and demographic data from donors who were malaria EIA reactive were analysed. Time since possible exposure was estimated and antibody survival modelled. Results Among seroreverters, the time since last possible exposure was significantly shorter in ‘Visitors’ than in ‘Residents’. The antibody survival modelling predicted 20% of previously EIA reactive ‘Visitors’, but only 2% of ‘Residents’ would become non‐reactive within 3 years of their first reactive EIA. Conclusion Antibody persistence in donors correlates with exposure category, with semi‐immune ‘Residents’ maintaining detectable antibodies significantly longer than non‐immune ‘Visitors’.     

输血前不规则抗体筛查的必要性

目的:分析不规则抗体筛查在临床配血过程前的影响,从而确定不规则抗体筛查在临床输血中的意义。方法:应用微柱凝胶免疫检测技术对2013年期间3 511例临床申请输血患者标本进行不规则抗体筛查,确定阳性检出者对临床配血的影响。结果:临床申请输血患者标本3 511例中检出不规则抗体34例,阳性率0.97%。不规则抗体阳性患者血型系统,Rh系统29例(85.29%);MNSs系统4例(11.77%);Kidd 1例(2.94%)。结论:鉴定红细胞抗体,则有可能检查出ABO血型系统之外的不规则抗体,而此抗体与相应抗原发生免疫反应,可导致溶血性输血反应的发生。因此对术前备血和需要输血治疗的备血患者做抗体筛选试验,从而有利于为患者找到合适的血液输注,保证输血安全、有效。     

输血前血型和抗体筛检与医疗风险的相关性探讨

目的：探讨输血前血型和抗体筛检工作的重要性及其与医疗风险的相关性。方法：对2814例备血患者,特别是外科患者ABO血型、Rh血型、不规则抗体检查结果和用血情况进行统计分析。结果：2814例备血患者中A型895例（31．81％）,B型736例（26．15％）,O型881例（31．31％）,AB型302例（10．73％）;Rh阴性17例（0．60％）,其中2例因手术前未备血而引发了医疗纠纷,5例患者因备血不及时而延期手术;检出不规则抗阳性者6例（0．21％）,其中2例患者未能及时找到相合的血液,不能及时进行输血治疗而引起患者不满;外科备血2092例,有1097例（52．44％）只进行了检查而没有输血。结论：对外科手术患者术前常规进行血型鉴定和抗体筛检是安全输血的重要保证,它关系到能否及时为患者提供合适的血液制品进行输血治疗,必须引起高度重视,避免潜在的医疗风险和由此引发的医疗纠纷。     

Donor screening for hepatitis B virus infection in a cell and tissue bank

Abstract: Background and objectives. Hepatitis B virus (HBV) has been transmitted by tissue transplantation. In order to reduce the risk of HBV transmission, testing for antibody to HBV core antigen (anti‐HBc) is used in addition to testing for hepatitis B surface antigen (HBsAg) in many blood centers and tissue banks. Design and methods. We retrospectively analyzed the results of HBV assays in tissue donors. All tissue donors were tested for HBsAg and anti‐HBc. All anti‐HBc positive sera were tested for the antibody to HBsAg (anti‐HBs). From July 2006, an HBV nucleic acid testing (NAT) assay was also performed. Results. A total of 6855 tissue donors from January 1999 till July 2007 were tested for HBV assays: 4756 women and 2099 men. Positive HBsAg was found in 23 (0.36%) living donors, while no multiorgan or cord blood (CB) donor was found to be positive for HBsAg. Positive anti‐HBc was found in 80 multiorgan donors (12.94%), 599 living donors (17.84%), and 103 CB donors (3.57%) (P<0.005), while isolated anti‐HBc was found in 12 multiorgan (1.94%), in 126 living tissue donors (3.75%), and in 8 CB donors (0.28%). A total of 1310 donors were analyzed for single‐sample DNA HBV NAT assay. Discussion. We consider that anti‐HBc and NAT assays must both still be performed in addition to HBsAg assay for HBV screening in tissue donors. All these tests will be useful in order to define an algorithm for safe and efficient management of the tissue bank.     

天津市2005-2006年HIV抗体人群筛查情况分析

目的分析天津市2005-2006年人群艾滋病病毒(HIV)抗体筛查检测数据,初步评估现行的筛查检测策略。方法对天津市艾滋病检测筛查实验室送检的601份样品,依据《全国艾滋病检测技术规范(2004年版)》规定的检测流程与方法进行HIV抗体确认。结果2005-2006年共对365份送检样品进行了确认试验,有215份为全条带阳性,确认为HIV抗体阳性。24份为特殊条带阳性,其中10例进行了随访,7例确认为HIV抗体阳性,3例排除HIV感染。51份确认试验结果为不确定,其中8例进行了随访,结果均确认为HIV抗体阴性。结论在医疗机构门诊及术前患者、公安和司法系统被监管人员等常规体检中,进行HIV抗体筛查是发现HIV感染者重要途径。对于不确定型、特殊阳性带型样品应慎重下结论,在随访检测的同时应积极考虑其他辅助手段。     

Alanine aminotransferase cut-off values for blood donor screening using the new International Federation of Clinical Chemistry reference method at 37 degrees C

BACKGROUND AND OBJECTIVES: Serum alanine aminotransferase (ALT) determination is recommended, or even required by law, in the screening of blood donors in many countries, and donors with an increased catalytic activity of ALT are excluded from blood donation. In most countries, the ALT cut-off value for blood donor screening for men and women is twice the upper limit of the normal range. The introduction, in 2002, of the new International Federation of Clinical Chemistry (IFCC) reference method, performed at 37 degrees C, required new ALT reference values to be established for healthy individuals and a new cut-off point to be determined for blood donor screening. MATERIALS AND METHODS: We compared ALT values of donor blood units using the previous German standard method, which measures ALT values at 25 degrees C, and the new IFCC reference procedure, where ALT levels are measured at 37 degrees C. RESULTS: We found a linear correlation between the ALT values obtained by the method at 25 degrees C and the new IFCC reference method (37 degrees C) (r = 0.983), and a gender- and age-independent ratio of 0.523. Using this ratio we calculated the new ALT cut-off for blood donations and now propose a new upper limit of 132 U/l (2.20 microkat/l) for men and 86 U/l (1.43 microkat/l) for women. Only 220 of 151 678 blood donations collected over a period of 5 years showed an ALT value higher than the cut-off. None were hepatitis C virus (HCV) positive in serological or nucleic acid amplification technology (NAT) assays. Only 0.006% of all blood donations were positive for antibody to HCV and thus excluded. CONCLUSIONS: With the implementation of the new IFCC reference method for ALT determination at 37 degrees C, we propose a new ALT cut-off for blood donor screening, which, for men, is about three times the upper limit of the normal range and for women about 2.5 times. Our results show that a lower cut-off would probably not yield a higher safety of blood products in terms of detecting viral infections, but would result in a loss of approximately 0.75% of suitable blood donors.     

广州市2003年HIV抗体初筛实验室质量评价

目的提高技术人员专业素质，提高实验室工作质量，促进全市艾滋病病毒（HIV）抗体初筛实验室的规范化建设，也为全国各省市HIV检测实验室的质量管理和质量评价提供参考。方法采用考评的方式：（1）发放一套质评血清（3份强阳性，2份弱阳性，5份阴性）；（2）采用问卷方式对各实验室的职能和质量管理工作进行调查；（3）根据质评血清检测和调查问卷填写的结果，抽取10家实验室进行现场实地考查。结果本市的49家初筛实验室参加考评，质评血清考核和问卷调查综合评分结果：优秀7家，良好24家，合格18家。现场实地考查结果，5家实验室顺利通过，5家被勒令整改。结论考评结果显示：广州市初筛实验室的质量水平均能满足目前工作需求，但按《全国艾滋病检测工作规范》要求，各实验室仍缺乏全面、系统、规范的质量管理体系，人员专业素质及检测技术水平还有待提高。     

113 229例住院患者HIV抗体初筛结果分析

目的：了解某大型医院住院患者人类免疫缺陷病毒（ HIV）抗体初筛阳性率及其在临床科室中分布情况。方法对113229例住院患者进行HIV抗体初筛检测,比较不同性别患者的阳性率,分析HIV抗体阳性患者在不同科室的分布情况。结果 HIV抗体初筛阳性152例,阳性率为0．134％;其中男91例（0．161％）,女61例（0．107％）,不同性别间阳性率比较差异有统计学意义（P＜0．05）。 HIV抗体初筛阳性患者分布于20个科室,其中高发科室有耳鼻喉科、骨科、妇科、泌尿外科、普外科、神经内科、皮肤科、肿瘤科、眼科。这些科室的HIV抗体初筛阳性者占总筛查阳性的67．1％。结论住院患者中存在较高的HIV抗体初筛阳性率,且科室分布广泛。     

天津市HIV抗体检测中的替代策略研究

目的分析天津市2007-2009年人群HIV抗体检测数据,确定替代策略应用方案。方法对于接收的天津市艾滋病检测筛查实验室送检的1 636份样品,依据《全国艾滋病检测技术规范（2004年版）》规定的检测流程与方法进行HIV抗体确证。结果 2007-2009年共有1 039份样品经确证为HIV抗体阳性,进行艾滋病疫情报告例数为690例。ELISA S/CO≥6且快速检测阳性的1 028份样品,确证结果均为阳性。ELISA与快速检测结果不一致的124份样品,无确证结果为阳性者。结论在HIV低流行区将替代策略引入日常HIV抗体筛查检测,可以提高检测效率。通过身份信息核查,可以有效避免对继往感染者的重复确证。     

HIV抗体筛查试验阳性-确证试验阴性标本的分析

目的了解HIV抗体筛查试验假阳性现象的特点及引起假阳性反应的原因。方法对2004～2009年本实验室常规监测检测中筛查试验阳性-确证试验阴性标本的相关资料进行分析。结果394例筛查试验阳性-确证试验阴性标本主要来源于没有或甚少高危行为的各类普通人群;采用"明胶颗粒凝集试剂(PA)+ELISA"或双ELISA试剂组合检测,83%以上为一阴一阳结果,近70%的标本ELISAS/CO值在1～4之间;采用"吉比爱ELISA+第3代梅里埃ELISA"或"吉比爱ELISA+第4代梅里埃ELISA"组合检测,S/CO值同处于1～6范围的标本分别占78.95%和64.0%。结论HIV抗体筛查检测假阳性存在主、客观原因;实验室应采取应对措施最大限度地保证结果的准确以及对检测结果进行正确的解释。     

Evidence that use of a second-generation hepatitis C antibody assay prevents additional cases of transfusion-transmitted hepatitis

SUMMARY. The aim of this study was to determine if using hepatitis C antibody (anti-HCV) enzyme immunoassay version 2.0 (EIA2) in addition to version 1.0 (EIA1) increased the safety of the blood supply. Blood non-reactive by anti-HCV EIA1 was transfused in 1990-92. Stored samples from 40098 units, donated prior to 13 March 1992 were later tested by EIA2. For donor units reactive for anti-HCV by EIA2. a recombinant immunoblot assay (RIBA2) was also carried out. In 63 cases, recipients of transfusions which were EIAZ negative or EIA2 reactive were tested for anti-HCV and elevated alanine aminotransferase (ALT) levels 9-1 2 months after transfusion: pretransfusion anti-HCV status of recipients was unknown. Among these multitransfused patients receiving units that were negative by both EIA1 and EIA2, 1/26 (4%) had anti-HCV. Among transfusion recipients of units negative by EIA1, but who received at least one unit reactive by EIA2,4/37 recipients (11%) were anti-HCV reactive (P = 0.59). For the recipients of EIA2 reactive blood, when the donor unit was RIBA2 non-reactive. 0/23 recipients were reactive by anti-HCV. Among the recipients of a RIBA2 indeterminate unit, 1/10 recipients had anti-HCV, but for patients who received at least one RIBA2 reactive unit, 3/4 recipients had anti-HCV (P = 0.0 3). Hence. second-generation anti-HCV testing detected additional units capable of transmitting hepatitis C that were not detected by first-generation testing. However, RIBA2 is a more specific method than EM2 for determining units capable of transmitting HCV.     

Documented cases of post-transfusion malaria occurring in England: a review in relation to current and proposed donor-selection guidelines

BACKGROUND AND OBJECTIVES: Although uncommon, five cases of transfusion-transmitted malaria have been documented in England over the last 20 years. With the reappearance onto the market of high-quality malaria antibody assays, and by utilizing the results of analysis of these five cases, it has been possible to review the donor malaria-deferral guidelines. MATERIALS AND METHODS: Details of the five cases of post-transfusion malaria were reviewed against the proposed new donor-deferral guidelines for malaria. RESULTS: Three of the five cases of post-transfusion malaria were directly attributable to the deferral guidelines, allowing infectious donors to be bled. CONCLUSIONS: The proposed new guidelines will prevent further cases of transmission from semi-immune individuals.