Is dual testing for hepatitis C necessary? Modelling the risk of removing hepatitis C antibody testing for Australian blood donations

BACKGROUND AND OBJECTIVES

Parallel testing of blood donations for hepatitis C virus (HCV) antibody and HCV RNA by nucleic acid testing (NAT) has been standard practice in Australia since 2000. Meanwhile, NAT technologies have improved, and HCV has become a curable disease. This has resulted in a significant reduction in the risk and clinical consequences of HCV transmission through transfusion. This study aimed to estimate the residual risk (RR) under various testing options to determine the optimal testing strategy.

MATERIALS AND METHODS

A developed deterministic model calculated the RR of HCV transmission for four testing strategies. A low, mid and high estimate of the RR was calculated for each. The testing strategies modelled were as follows: universal dual testing, targeted dual testing for higher risk groups (first-time donors or transfusible component donations) and universal NAT only.

RESULTS

The mid estimate of the RR was 1 in 151 million for universal dual testing, 1 in 111 million for targeted dual testing of first-time donors, 1 in 151 million for targeted dual testing for transfusible component donations and 1 in 66 million for universal NAT only. For all testing strategies, all estimates were considerably less than 1 in 1 million.

CONCLUSION

Antibody testing in addition to NAT does not materially change the risk profile. Even conservative estimates for the cessation of anti-HCV predict an HCV transmission risk substantially below 1 in 1 million. Therefore, given that it is not contributing to blood safety in Australia but consuming resources, anti-HCV testing can safely be discontinued.

The proportion and trend of human immunodeficiency virus infections associated with men who have sex with men from Chinese voluntary blood donors: a systematic review and meta-analysis

BACKGROUND

Human immunodeficiency virus (HIV)-positive cases associated with men who have sex with men (MSM) have rapidly increased over the past years. The objective of this study is to comprehensively evaluate the proportions, changing trends, and geographical distribution of MSM-associated HIV cases from Chinese voluntary blood donors by systematically reviewing the available literature.

STUDY DESIGN AND METHODS

Major English and Chinese research databases were searched for studies reporting study locations, study years, the number of HIV infections among blood donors, and the number of HIV-positive donations associated with MSM in China. The proportion estimates were calculated; subgroup analyses and test for time trend were performed using software of comprehensive meta-analysis.

RESULTS

Thirty-four studies met eligibility criteria. The pooled proportion of HIV-positive donations associated with MSM from 2001 to 2012 was 36.5% (95% confidence interval, 29.6%-44.1%). The epidemic was found to be more severe in northeast and north China compared to south China (59.6%; 55.0% vs. 3.8%, respectively). The proportion showed a significantly increasing trend over the study period (10.3% in 2001-2005; 38.6% in 2006-2009; and 47.6% in 2010-2012; trend test chi-square = 16.42, p < 0.001).

CONCLUSION

The relatively high proportion of MSM- associated HIV-positive donors is of concern. Efficient and effective measures focused on public education and improving knowledge of blood safety are needed to prevent this at-risk population from seeking HIV testing through blood donation. It is also imperative to expand the scope of postdonation nucleic acid testing to shorten the window period to improve blood supply safety in China.

Residual Risk of Hepatitis-B-Infected Blood Donations: Estimation Methods and Perspectives

Despite a considerable reduction of the risk of HBV-infected blood donation entering blood supply (residual risk) due to improved screening by HBV NAT in the developed countries, the bulk of the people with HBV living in the developing countries still needs to be screened by serologic tests such as HBsAg and anti-HBc. Many of these countries lack resources for implementing NAT and are likely to remain so in the next decade or longer, thus depending on the HBV residual risk monitoring based on serologic testing and corresponding estimation methods. This paper reviews main HBV residual risk findings worldwide and the methods based on serology used for their calculation with repeat donors, as well as their extension to the first-time donors. Two artificial datasets with high (4.36%) and low (0.48%) HBV prevalence were generated to test the performance of five methods: the original incidence/window-period model based solely on HBsAg, its modification by Soldan in 2003, the Müller-Breitkreutz model, the HBsAg yield model, and its extension to include anti-HBc seroconversions within a year. The last model was closest to the true values of residual risk and had smallest variation of the estimates in both high and low prevalence data. It may be used for residual risk evaluation in relatively small samples, such as regional blood banks data.

p73 plays a role in erythroid differentiation through GATA1 induction

The TP73 gene gives rise to transactivation domain-p73 isoforms (TAp73) as well as DeltaNp73 variants with a truncated N terminus. Although TAp73alpha and -beta proteins are capable of inducing cell cycle arrest, apoptosis, and differentiation, DeltaNp73 acts in many cell types as a dominant-negative repressor of p53 and TAp73. It has been proposed that p73 is involved in myeloid differentiation, and its altered expression is involved in leukemic degeneration. However, there is little evidence as to which p73 variants (TA or DeltaN) are expressed during differentiation and whether specific p73 isoforms have the capacity to induce, or hinder, this differentiation in leukemia cells. In this study we identify GATA1 as a direct transcriptional target of TAp73alpha. Furthermore, TAp73alpha induces GATA1 activity, and it is required for erythroid differentiation. Additionally, we describe a functional cooperation between TAp73 and DeltaNp73 in the context of erythroid differentiation in human myeloid cells, K562 and UT-7. Moreover, the impaired expression of GATA1 and other erythroid genes in the liver of p73KO embryos, together with the moderated anemia observed in p73KO young mice, suggests a physiological role for TP73 in erythropoiesis.

Experience of mandatory nucleic acid test (NAT) screening across all blood organizations in Germany: NAT yield versus breakthrough transmissions

BACKGROUND

Mandatory nucleic acid test (NAT) blood screening was introduced in Germany in 1999 for hepatitis C virus (HCV) RNA and in 2004 for human immunodeficiency virus Type 1 (HIV-1) RNA. Minimal sensitivity limits of 5000 IU HCV RNA/mL and 10,000 IU HIV-1 RNA/mL were defined for the individual donation facilitating testing of minipools (MPs). The NAT yield obtained from all blood organizations is summarized. Transfusion-associated virus transmissions despite NAT screening ("breakthrough transmissions") are analyzed.

STUDY DESIGN AND METHODS

In Germany, a variety of NAT assays is applied for NAT screening pool sizes of up to 96 donations. Subsets of NAT yield cases were characterized with regard to viral loads by quantitative NAT and with regard to viral genotypes. Confirmed breakthrough transmissions were analyzed using different molecular and serologic assays.

RESULTS

Ninety-two HCV NAT yield cases among 40.8 million and 11 HIV-1 NAT yield cases among 17.1 million donations were identified. During this period, one transmission case was confirmed for HCV and one for HIV-1. The two incidents escaped NAT detection because of low-level viremia and/or suboptimal amplification efficiency. Evidence was obtained for a case of HIV-1 nontransmission by a low-level HIV-1 contaminated red blood cell unit.

CONCLUSION

NAT screening of MPs identified the vast majority of window-phase donations. A significant number of transmission cases was interdicted; breakthrough transmissions may still occur as rare events, even with individual-donation NAT in place. Sensitivity limits might be adapted to the current "state of the art" taking account of viral dynamics during early infection, incidence rates, and costs.

A method for estimating incidence rate of infectious diseases among first-time blood donors

BACKGROUND

In certain circumstances, there is no method for estimating incidence based on testing results on a single blood sample from first-time blood donors, severely limiting the ability to assess the residual risk of blood-borne infections among this donor subpopulation.

STUDY DESIGN AND METHODS

Incidence rates were estimated for human immunodeficiency virus (HIV) and hepatitis C virus (HCV) among first-time donors using the formula (P(2) - P(1))/D, where P(1) is the prevalence among blood donations from first-time donors of the minimum eligible ages for donation, P(2) is the prevalence among donations from first-time donors of an older age group, and D is the age difference (in years) between the older and younger donor groups.

RESULTS

Estimating incidence among first-time donors using the proposed method based on a single test for anti-HCV produced similar results to those based on HCV nucleic acid test (NAT) yield cases, by sex and in different periods. Comparison of the proposed method with HIV NAT yield also showed similar results although the small number of HIV NAT yield cases limits interpretation.

CONCLUSIONS

The proposed method provides an alternative way for estimating incidence of certain blood-borne infections among first-time donors, provided that our assumptions are met. It helps residual risk assessment in donor populations where first-time donors account for most of the donations and only one test result is available for each donor.

Experience of German Red Cross blood donor services with nucleic acid testing: results of screening more than 30 million blood donations for human immunodeficiency virus-1, hepatitis C virus, and hepatitis B virus

BACKGROUND

The risk of transfusion-transmitted human immunodeficiency virus-1 (HIV-1), hepatitis C virus (HCV), and hepatitis B virus (HBV) infections is predominantly attributable to donations given during the early stage of infection when diagnostic tests may fail. In 1997, nucleic acid amplification technique (NAT)-testing was introduced at the German Red Cross (GRC) blood donor services to reduce this diagnostic window period (WP).

STUDY DESIGN AND METHODS

A total of 31,524,571 blood donations collected from 1997 through 2005 were screened by minipool NAT, predominantly with pool sizes of 96 donations. These donations cover approximately 80 percent of all the blood collected in Germany during that period. Based on these data, the WP risk in the GRC blood donor population was estimated by using a state-of-the-art mathematic model.

RESULTS

During the observation period, 23 HCV, 7 HIV-1, and 43 HBV NAT-only-positive donations were detected. On the basis of these data and estimated pre-NAT infectious WPs, the residual risk per unit transfused was estimated at 1 in 10.88 million for HCV (95% confidence interval [CI], 7.51-19.72 million), 1 in 4.30 million for HIV-1 (95% CI, 2.39-21.37 million), and 1 in 360,000 for HBV (95% CI, 0.19-3.36 million). Based on observed cases of breakthrough infections, the risk of transfusion-related infections may be even lower.

CONCLUSION

The risk of a blood recipient becoming infected with HCV, HIV-1, or HBV has reached an extremely low level. Introduction of individual donation testing for HCV and HIV-1 would have a marginal effect on interception of WP donations.

Payment for whole blood donations in Lithuania: the risk for infectious disease markers

BACKGROUND AND OBJECTIVES

In Lithuania, remuneration for whole blood donations still prevails, with the government covering payment for the donors. The payment per donation in cash is equal to 40 litas (euro11.6); it is offered to all blood donors and accepted by the majority of them. Donors who gave blood and received the payment are treated as remunerated donors; those who gave blood and did not take the payment are treated as non-remunerated ones. The purpose of this study was to assess the risk of payment for whole blood donations and to analyse the prevalence of infectious diseases markers per 100 remunerated and non-remunerated, first-time and regular whole blood donations, and to compare the risk ratios of infectious disease markers of remunerated and non-remunerated whole blood donations in 2005 and 2006 at the National Blood Center in Lithuania.

MATERIALS AND METHODS

Whole blood donors were categorized as follows: (i) first-time donor, remunerated; (ii) first-time donor, non-remunerated; (iii) regular donor, remunerated; and (iv) regular donor, non-remunerated. The blood donations were analysed for the presence or absence of the following infectious disease markers: anti-hepatitis C virus (anti-HCV), hepatitis B surface antigen (HBsAg), anti-human immunodeficiency virus (anti-HIV (1)/(2)) and syphilis. Only confirmed infectious disease markers were classified. To assess the risk of payment for whole blood donations, the prevalence of infectious disease markers per 100 donations in the different donor groups and the risk ratios between the remunerated and non-remunerated donations were determined.

RESULTS

The prevalence per 100 first-time remunerated donations was: for anti-HCV 1.84 (2005) and 2.98 (2006); for HBsAg 1.73 (2005) and 2.03 (2006); for syphilis 0.67 (2005) and 1.03 (2006). The prevalence per 100 first-time non-remunerated donations was: for anti-HCV 0.93 (2005) and 0.98 (2006); for HBsAg 1.57 (2005) and 1.33 (2006); for syphilis 0.29 (2005) and 0.47 (2006). The first-time donors who were remunerated for whole blood donations had a significantly higher prevalence of infectious disease markers per 100 donations and a higher risk ratio for at least three infectious disease markers (HBsAg, anti-HCV and syphilis) as compared to first-time donors who were non-remunerated. The regular donors who were non-remunerated for whole blood donations had the lowest prevalence of all infectious disease markers: anti-HCV -0.03 (2005) and 0.04 (2005); syphilis -0.06 (2005) and 0.02 (2006); and any positive cases of HBsAg and anti-HIV (1)/(2) were found both in 2005 and 2006. No statistically significance differences in incidence and risk ratio existed when comparing the regular donations who were remunerated and non-remunerated.

CONCLUSION

The payment for whole blood donors provides a higher risk for infectious disease markers of first-time donations at the National Blood Center in Lithuania.

An audit of gynaecological procedures in Jehovah's Witnesses in an inner city hospital

A retrospective study of Jehovah Witness women between January 1994 and December 2003 was performed. Gynaecologists are concerned about operating on Jehovah's Witnesses because of the potential for haemorrhage during surgery. Jehovah's Witnesses do not accept donor blood but some will permit their own blood to be stored pre-operatively and administered during surgery if deemed necessary. Approximately 150,000 Jehovah's Witnesses live in the UK but little on gynaecological procedures in Jehovah's Witnesses has been published. There were 64 procedures (14 major, 18 intermediate and 32 minor) in 53 women with a median age of 42 years. There were no perioperative deaths, but postoperative anaemia was common. Our study showed that major, intermediate and minor gynaecological procedures can be performed without significant morbidity on Jehovah's Witnesses but a protocol should be available to outline management of those who refuse blood.

Residual risk of transfusion transmitted human immunodeficiency virus, hepatitis B virus, hepatitis C virus and human T lymphotrophic virus

BACKGROUND

The risk of transfusion transmitted viral infection is now so low that mathematical modelling is required to estimate the residual risk. The first national viral risk estimates for hepatitis B virus (HBV), human immunodeficiency virus (HIV) and hepatitis C virus (HCV) were recently published by the Australian Red Cross Blood Service. Using several refinements to the original methodology, as well as an additional 2 years of data, new risk estimates have been derived.

METHODS

Viral screening data for Australian donors for 2000/2003 were retrospectively analysed. The data were applied to three published models to estimate the residual risk of transmitting HIV, HBV, HCV or human T lymphotrophic virus (HTLV) by blood transfusion in Australia.

RESULTS

Applying the three models to HBV, HIV and HCV, three point estimates of the residual risk per unit were calculated for each virus. The median point estimates were 1 in 1,339,000 for HBV, 1 in 1 in 7,299,000 for HIV, and 1 in 3,636,000 for HCV. Although the HTLV risk could not be equivalently calculated because of the lack of incident infection it was estimated to be considerably less than 1 in 1,000,000 using a separate method.

CONCLUSIONS

The most current and accurate estimate of residual risk of viral transmission in Australia has been provided in the present study. The residual risk in Australia is exceptionally small, continuing to decrease and is generally less than European or US risk estimates. These new estimates demonstrate that for viral transmission the Australian blood supply is amongst the safest in the world, and provide a basis for evaluating the cost benefit of future viral testing methodologies.

Cost-effectiveness of pathogen inactivation for platelet transfusions in the Netherlands

The objective of this study is to estimate cost-effectiveness of pathogen inactivation for platelet transfusions in the Netherlands. We used decision tree analysis to evaluate the cost-effectiveness of the addition of pathogen inactivation of pooled platelets to standard procedures for platelet transfusion safety (such as, donor recruitment and screening). Data on transfusions were derived from the University Medical Centre Groningen (the Netherlands) for 1997. Characteristics of platelet recipients (patient group, age, gender and survival) and data/assumptions on viral and bacterial risks were linked to direct and indirect costs/benefits of pathogen inactivation. Post-transfusion survival was simulated with a Markov model. Standard methods for cost-effectiveness were used. Cost-effectiveness was expressed in net costs per life-year gained (LYG) and estimated in baseline- and sensitivity analysis. Sensitivity was analysed with respect to various assumptions including sepsis risk, reduction of the discard rate and discounting. Stochastic analysis to derive 90% simulation intervals (SIs) was performed on sepsis risk. Net costs per LYG for pathogen inactivation were estimated 554,000 euro in the baseline-weighted average over the three patient groups (90% SI: 354,000-1092,500 euro). Sensitivity analysis revealed that cost-effectiveness was insensitive to viral risks and indirect costing, but highly sensitive to the assumed excess transfusions required and discounting of LYG. Given relatively high net costs per LYG that are internationally accepted for blood transfusion safety interventions, our estimated cost-effectiveness figures for pathogen inactivation may reflect acceptable cost-effectiveness in this specific area. Two main assumptions of our model were that the pathogen inactivation was 100% effective in preventing transmission of the pathogens considered and was not associated with major and/or costly adverse reactions. Validation of several crucial parameters is required, in particular the Dutch risk for acquiring and dying of transfusion-related sepsis.

Screening of blood donors for hepatitis C virus RNA with the MagNA Pure-COBAS AmpliScreen method

BACKGROUND

This report describes the validation results and the performance characteristics of a new, semiautomated minipool nucleic acid amplification method for testing of blood products to reduce the transmission of hepatitis C virus (HCV) by transfusions.

STUDY DESIGN AND METHODS

Minipools of 96 donations were prepared with the Tecan Genesis pipettors. Nucleic acids were isolated from plasma samples with the MagNA Pure LC instrument (Roche Diagnostics GmbH) and amplified and detected with the COBAS AmpliScreen second-generation HCV assay (Roche Molecular Systems, Inc.). Sensitivity of the method was determined with the WHO International Standard for HCV RNA (NIBSC 96/790) as a reference. The risk of cross-contamination during the nucleic acid extraction and postelution steps was studied with a highly viremic sample.

RESULTS

Detection limit of the assay (95% hit rate) was calculated to be 11.7 IU per mL. Altogether 2,423 minipools (232,600 donations) were screened with the following performance characteristics: initially false-reactive results (0%), failure of run control detection (0.45%), and failure of internal control detection (0.90%). Two cross-contamination cases caused by a highly viremic sample were found during the validation phase but not in the routine screening period, although nine HCV RNA-positive minipool samples were observed.

CONCLUSION

This combination of HCV RNA screening methods showed the detection limit that is well below the sensitivity requirements of the regulatory bodies. Robustness of the validated HCV RNA screening method has proved to be acceptable for routine screening of blood donors on a large scale.

A new strategy for estimating risks of transfusion-transmitted viral infections based on rates of detection of recently infected donors

BACKGROUND

Estimates for human immunodeficiency virus (HIV)-1 and hepatitis C virus (HCV) transfusion-transmitted risks have relied on incidence derived from repeat donor histories and imprecise estimates for infectious, preseroconversion window periods (WPs).

STUDY DESIGN AND METHODS

By use of novel approaches, WPs were estimated by back-extrapolation of acute viral replication dynamics. Incidence was derived from the yield of viremic, antibody-negative donations detected by routine minipool nucleic acid testing (MP-NAT) of 37 million US donations (1999-2002) or from sensitive/less-sensitive HIV-1 enzyme immunoassay (S/LS-EIA) results for seropositive samples from 6.5 million donations (1999). Incidences and WPs were combined to calculate risks and project yield of individual donation (ID)-NAT.

RESULTS

The HIV-1 WP from presumed infectivity (1 copy/20 mL) to ID-NAT detection was estimated at 5.6 days, and the periods from ID to MP-NAT detection and from MP-NAT to p24 detection at 3.4 and 6.0 days, respectively; corresponding estimates for HCV were 4.9, 2.5, and 50.9 days (the latter represents period from MP-NAT to HCV antibody detection). The HIV-1 incidence projected from MP-NAT yield or from S/LS-EIA data was 1.8 per 100,000 person-years, resulting in a corresponding HIV-1 transfusion-transmitted risk of 1 in 2.3 million. The HCV incidence from MP-NAT yield was 2.70 per 100,000 person-years with a corresponding risk of 1 in 1.8 million donations. Conversion from MP-NAT to ID-NAT was projected to detect two to three additional HIV-1 and HCV infectious units annually.

CONCLUSIONS

MP-NAT yield and S/LS-EIA rates can accurately project transfusion risks. HCV and HIV-1 risks, currently estimated at 1 per 2 million units, could be reduced to 1 in 3 to 4 million units by ID-NAT screening.

Infectious Risks Associated with the Transfusion of Blood Components and Pathogen Inactivation in Japan

Even after the implementation of the nucleic acid amplification testing (NAT) system, there remains a residual risk of viral transmission through blood transfusion because of the limited sensitivity of the reagents used and the pooling strategy of the current NAT system. From the calculation using NAT yield and the length of the window period, we presume that we will obtain 0.75 donations for human immunodeficiency virus and 0.58 donations for hepatitis C virus annually that are individual donation-NAT positive but 50-individual pool-NAT negative, figures that are comparable with those in other developed countries. The number of donations potentially positive for the hepatitis B virus genome is, however, considerably high in Japan and is estimated to be more than 100 annually, which is the sum of the donors in the minipool-NAT window period and the chronic carriers with a low viral load. The incidence of bacterial sepsis after transfusion is relatively low in Japan. This incidence is possibly attributable to the short shelf lives of platelet concentrate and red blood cell component, which are 3 and 21 days, respectively. In Japan, the implementation of a new technology to screen out or abrogate infectious agents in blood components is necessary while considering the balance between benefits and possible new risks or costs.

Evaluation of processing characteristics of photochemically treated pooled platelets: target requirements for the INTERCEPT Blood System comply with routine use after process optimization

To ensure good performance of pathogen inactivation with the INTERCEPT blood system, specific target requirements must be met for platelet dose, volume, plasma content and residual red blood cells (RBCs) prior to photochemical treatment (PCT). A two-arm in vitro study was conducted to compare quality parameters of pooled platelet concentrates (PCs), either treated (test units) or nontreated (control units). PCs meeting European requirements were evaluated with reference to their compliance with INTERCEPT guard bands. Of 50 PCs (25 tests and 25 controls) meeting European quality requirements, 24% (three test and three controls units) did not reach INTERCEPT requirements, particularly in terms of sufficient volumes and RBC contamination. The buffy-coat optimization procedure assessed prior to this study ensured plasma contents well within target limits of 30 to 45%. Due to PCT-related in-process loss of 11% in volume (34.38 +/- 3.94) and in platelet dose (0.41 +/- 0.14), the mean platelet dose was significantly (P < 0.001) lower in test units: 3.1 +/- 0.3 versus 3.6 +/- 0.4 x 10(11). After treatment, six of the overall 25 test units (25%) would not have met the European guideline for platelet dose (3.0 x 10(11)). Before implementation of techniques for pathogen reduction, each centre should optimize processing steps during a validation procedure to ensure PC complying with INTERCEPT targets before and European targets after treatment. Besides buffy-coat optimization for sufficient plasma reduction, centrifugation profiles need to be optimized as well to prevent PC with low volumes and, in particular, with higher than acceptable RBC contamination.

Preclinical safety profile of plasma prepared using the INTERCEPT Blood System

BACKGROUND AND OBJECTIVES

The newly developed INTERCEPT Blood System for plasma uses the addition of a new psoralen, amotosalen HCl (AMOTOSALEN), followed by illumination with ultraviolet A light, to inactivate viruses, bacteria, protozoa and leucocytes that may contaminate fresh-frozen plasma (FFP). Extensive toxicology studies were performed to characterize the safety of the photochemical treatment process for its intended use with plasma.

MATERIALS AND METHODS

The studies of general toxicology, safety pharmacology, phototoxicity, reproductive toxicity and venous irritation, summarized in this review, provide a comprehensive toxicology profile for photochemically treated 100% plasma.

RESULTS

No specific target organ toxicity (based on clinical or histological pathology), phototoxicity, or reproductive toxicity was observed.

CONCLUSIONS

The results of an extensive series of studies have demonstrated no toxicologically relevant effects of photochemically treated 100% plasma prepared using the INTERCEPT Blood System for plasma.

Follow-up of six blood donors highlights the complementary role and limitations of hepatitis C virus antibody and nucleic acid amplification tests

BACKGROUND AND OBJECTIVES

The purpose of this study was to analyse the follow-up results for six blood donors who screened positive for hepatitis C virus (HCV) by nucleic acid amplification technology (NAT) but were non-reactive in the primary antibody immunoassay (HCV NAT yield).

MATERIALS AND METHODS

Volunteer blood donations were screened, in parallel, for antibodies to hepatitis C virus (anti-HCV) and for human immunodeficiency virus (HIV)/HCV RNA using the Abbott PRISM HCV Chemiluminescent immunoassay (ChLIA) and the Chiron Procleix HIV-1/HCV RNA assays, respectively. NAT yield donor samples were further tested using supplemental assays, including an alternate HCV antibody enzyme immunoassay (EIA) (Abbott Murex anti-HCV Version 4), an immunoblot (Ortho RIBA-3 or Genelabs Diagnostics HCV Blot 3.0) and two alternative HCV NAT assays [Roche HCV Amplicor and an assembled HCV polymerase chain reaction (PCR)]. Five of the six donors were available for follow-up testing.

RESULTS

The six NAT yield donations were identified as constituents of 24-member minipools among 2,212,695 donations screened over the 28-month study period. All samples were positive when tested, undiluted, using the Roche Amplicor and assembled reverse transcription-polymerase chain reaction (RT-PCR) alternate NAT assays. One of the donors, subsequent to seroconversion, showed RNA levels that fluctuated above and below the limit of detection of the NAT screening assay. Three of the six were reactive on the secondary EIA and showed reactivity to the core c22(p) antigen by immunoblot at the index donation. Two others subsequently became reactive in the ChLIA prior to the EIA, showing reactivity against c100 and/or c33c antigens by immunoblot. The remaining donor became reactive in the ChLIA and EIA at the same time, showing RIBA reactivity against all of the following three peptides: c100; c33c; and c22(p).

CONCLUSIONS

This study demonstrated that at least five of six HCV NAT yield donors were in the pre- or early antibody seroconversion phase of infection. The observation that one yield donor demonstrated HCV RNA that fluctuated above and below the limit of detection of the primary NAT-screening assay supports the maintenance of both NAT and antibody screening for HCV. Follow-up testing of suspected yield donors revealed that the primary and alternate anti-HCV immunoassays had different performance characteristics, depending on the specificity of the donor's early anti-HCV response.

Estimation of the risk of hepatitis B virus, hepatitis C virus and human immunodeficiency virus infectious donations entering the blood supply in England, 1993-2001

BACKGROUND AND OBJECTIVES

The frequency of hepatitis B virus (HBV), hepatitis C virus (HCV) or human immunodeficiency virus (HIV) infectious donations entering the blood supply in England is too low to monitor using observational studies. The expected frequency of infectious donations can be estimated and these estimates may be used to contribute to monitoring of blood safety and used in the design of strategies to decrease the risk of transfusion-transmitted infections.

MATERIALS AND METHODS

The prevalence and incidence of hepatitis B surface antigen (HBsAg), and antibodies to HCV and HIV (anti-HCV and anti-HIV, respectively) in donors in England, between 1993 and 2001, were used together with data about the length of negative 'window-periods' of current assays for each of these markers and data about test performance, to estimate the number of infectious donations that enter the blood supply. The risks were calculated separately for donations from new donors and from repeat donors, and for the three time periods 1993-95, 1996-98 and 1999-01.

RESULTS

The estimated frequency of infectious donations entering the blood supply in England, between 1993 and 2001 was 1 in 260,000 for HBV and 1 in 8 million for HIV. For HCV, the frequency of infectious donations was 1 in 520,000 during 1993-98 and fell to 1 in 30 million during 1999-2001 when all donations were tested for HCV RNA. The frequency of HBV- and HCV-infectious donations entering the blood supply fell over these 9 years: the frequency of HIV-infectious donations remained essentially unchanged. The risk from donations from new donors was found to be approximately sevenfold higher than the risk from donations from repeat donors.

CONCLUSIONS

The risks of HBV-, HCV- or HIV-infectious donations entering the blood supply in England are very low, and have decreased since 1993. Although the accuracy of these estimates is imperfect, mainly owing to uncertainty in some assumptions and to small numbers of infections, they provide some quantification of the risk of HBV, HCV or HIV transmission by transfusion, and allow comparison of the magnitude of these risks for each infection and over time. The methods we have used have been developed and improved from previously published methods.

Ultrastructural and phenotypic analysis of in vitro erythropoiesis from human cord blood CD34+ cells

Erythropoietin (EPO) induces erythropoiesis in vitro as well as in vivo, and the process of erythroid differentiation has been explored phenotypically and morphologically. However, morphological analysis of in vitro erythropoiesis of human hematopoietic progenitor cells at the ultrastructural level has not been reported before. In the present study, we have traced the ultrastructural changes of erythroid differentiation during ex vivo expansion of human cord blood (CB) CD34(+) cells in the presence of EPO by electron microscopy (EM), along with concurrent phenotypic analysis. CD34(+) cells purified from ten CBs by immunomagnetic selection were cultured in serum-free essential media in the presence of a combination of the several cytokines including EPO, thrombopoietin, flt3-ligand (FL), stem cell factor (SCF), granulocyte colony-stimulating factor, interleukin (IL)-3 and/or IL-11. Phenotypic analysis was performed by flow cytometric analysis for erythroid markers, including glycophorin C (GPC), Kell-related, glycophorin A (GPA), band 3, Lu(b), and RhD. Ultrastructural analysis was performed by electron-microscopic examination of the cultured cells stained with uranyl acetate and lead citrate. Phenotypic analysis revealed that in the absence of EPO, genuine erythroid fraction expressing the typical pattern of erythroid markers did not appear. The order of the above markers expressed in the cultured cells in the presence of EPO was GPC, Kell-related, GPA, band 3, Lu(b), and RhD, irrespective of the type of cytokine added. Of the cytokines used in combination with EPO, FL + IL-3 was the most efficient in inducing erythroid differentiation, which was followed by SCF + IL-3. EM examination demonstrated complete process of erythroid development from pronormoblasts to reticulocytes with nuclei having been extruded and mature erythrocytes. These results suggest that morphologically intact erythrocytes could be produced by ex vivo expansion of CB CD34(+) cells using EPO.

Fluctuation of HCV viral load before seroconversion in a healthy volunteer blood donor

BACKGROUND

Newly implemented NAT has been shown to be able to effectively identify HCV-positive blood donated during the preseroconversion period.

STUDY DESIGN AND METHODS

EDTA-plasma pools of 24 donations were tested using an HIV-1/HCV multiplex NAT under an FDA-approved IND application. Samples in a positive pool were retested individually. Positive samples were further tested by two discriminatory assays to determine specific viral reactivity. Upon obtaining informed consent, seronegative donors with positive NAT results were enrolled into a follow-up study for risk factor analysis and laboratory testing.

RESULTS

A donation by a 29 year old female was identified as HCV NAT-positive with negative serology and an elevated ALT. Her two previous donations, 5 and 12 months earlier, were both seronegative and with normal ALT. Her husband tested positive for HCV RNA. The donor remained seronegative for at least 36 days. The index donation had a viral RNA concentration of >500,000 copies per mL while the first seropositive sample was NAT-negative. Laboratory data on serial follow-up samples showed 100- to 1,000-fold fluctuations in viral load during a period of 48 days prior to seroconversion.

CONCLUSIONS

This case suggests that, at least in some newly infected individuals, the HCV viral load can fluctuate dramatically prior to seroconversion, and that NAT, even on individual samples, will not totally prevent HCV transmission.

Nucleic acid technology screening of Australian blood donors for hepatitis C and human immunodeficiency virus-1 RNA: comparison of two high-throughput testing strategies

BACKGROUND AND OBJECTIVES

The aim of this study was to compare the performance of two high-throughput strategies for hepatitis C virus (HCV) and human immunodeficiency virus-1 (HIV-1) RNA nucleic acid technology (NAT) screening in a volunteer blood-donor population.

MATERIALS AND METHODS

The semiautomated Chiron Procleix HIV-1/HCV transcription mediated amplification (TMA) assay was used to screen 1 439 765 donations in two different testing configurations. Three sites (termed PDT sites) performed a mixture of individual donation (ID) and minipool (MP) testing, where 1 113 288 donations were screened as pools of 24 and an additional 32 003 donations were screened in ID format. A further two sites (termed SDT sites) screened 294 474 donations exclusively in ID format.

RESULTS

A significantly higher proportion of initial NAT reactives that failed to react on follow-up testing [termed non-repeatably reactive (NRR)] was observed for ID testing at SDT sites than at PDT sites (0.082 vs. 0.047%: P < 0.01). Within the PDT sites, however, there was no significant difference between the NRR rate for MP or ID samples (0.037 vs. 0.047%; not significant). There was a significant difference in failed run rates between PDT and SDT sites (P < 0.01), with PDT sites having a higher run failure rate owing to non-amplification of the internal control. The PDT sites also had a significantly higher overall invalid sample rate. However, the invalid sample rate, specifically caused by known equipment failure, was significantly higher in the SDT sites, possibly attributable to greater usage (P < 0.0001). Four HCV NAT-positive/antibody-negative samples were identified in the course of the study.

CONCLUSIONS

The comparison of the performance of PDT with SDT sites identified only minor differences that did not adversely impact on the timely release of blood products. Although both ID and MP strategies showed excellent specificity, irrespective of site configuration, the significantly increased NRR rate, observed exclusively for ID testing performed at SDT sites, indicates a potential for contamination that may limit the number of samples that can optimally be processed using ID testing. The performance data for ID testing in particular should serve as a useful benchmark for evaluating candidate NAT systems that are fully automated.

The first large-scale nucleic acid amplification testing (NAT) of donated blood using multiplex reagent for simultaneous detection of HBV, HCV, and HIV-1 and significance of NAT for HBV

The first nationwide nucleic acid amplification testing (NAT) for hepatitis B virus (HBV), hepatitis C virus (HCV), and human immunodeficiency virus type 1 (HIV-1) of voluntarily donated blood after serological pre-screening and before release of cellular components and plasma for fractionation was implemented by the Japanese Red Cross Blood Transfusion Services. From February 1, 2000 to April 30, 2001, specimens from 6,805,010 units of serologically negative donation were screened in minipools of 50 samples within 24 hr after blood donation by NAT using multiplex HBV/HCV/HIV-1 reagent for blood transfusion including short shelf-life platelets. Among them, 112 HBV DNA-positives, 25 HCV RNA positives and 4 HIV-1 RNA positives were screened out and we could prevent transfusion of these NAT positive units. Subtypes/genotypes of HBV DNA, adr/C, adw/A, adw/B, adw/C, ayr/C and ayw/D were found and adr/C was predominant. A total of 61.6 % of them (69/112) were negative by overnight EIA. Sixth three of HBV NAT-positive samples carried virus loads less than 10(4) copies/mL and 92.1 % of them (58/63) were negative by overnight EIA. The virus growth curves of HBV in 6 cases obtained by retrospective and prospective follow-up study showed exponential straight lines in the early stage of serological window periods and the log times of HBV growth (10 fold increase) in serological window period were between 4.6 and 7.6 days. NAT screening with highly sensitive reagents in pool of specimens is useful to exclude blood units with low level of HBV and HBV mutants from blood transfusion.

The anemia of vitamin A deficiency: epidemiology and pathogenesis

OBJECTIVE

To gain insight into vitamin A deficiency as a cause of anemia.

METHODS

Comprehensive review of the scientific literature.

RESULTS

Although vitamin A deficiency is recognized to cause anemia, 'vitamin A deficiency anemia' lacks complete characterization as a distinct clinical entity. Vitamin A appears to be involved in the pathogenesis of anemia through diverse biological mechanisms, such as the enhancement of growth and differentiation of erythrocyte progenitor cells, potentiation of immunity to infection and reduction of the anemia of infection, and mobilization of iron stores from tissues. Epidemiological surveys show that the prevalence of anemia is high in populations affected by vitamin A deficiency in developing countries. Improvement of vitamin A status has generally been shown to reduce anemia, but the actual public health impact on anemia is unclear.

CONCLUSIONS

Further work is needed to elucidate the biological mechanisms by which vitamin A causes anemia. The inclusion of anemia as an outcome measure in future micronutrient intervention studies should help provide further insight into the anemia of vitamin A deficiency.

Practical management of anticoagulation, bleeding and blood product support for cardiac surgery part two: Transfusion issues

We summarise recent advances in transfusion medicine applicable to cardiac surgery and cardiac transplantation. It is important that clinicians know the risks of blood transfusion in Australia. They should also be aware of the different types of transfusion reaction so that there is early recognition and investigation. Blood conservation strategies including acceptance of normovolaemic anaemia in clinically stable patients are important in reducing the requirement for red cell transfusion. Cytomegalovirus (CMV) seronegative blood products are recommended for heart transplant recipients with no evidence of prior CMV infection. Leucodepletion of units of unknown CMV status reduces the risk of CMV infection and are an acceptable alternative when seronegative units are unavailable. Leucodepletion of cellular blood products has been shown to reduce infection rates postoperatively in a large trial involving cardiac surgical patients. Further studies are needed to confirm this promising finding. Irradiation of blood products eliminates the risk of transfusion-associated graft versus host disease. Routine preoperative screening for cold agglutinins is no longer recommended.

Variant Creutzfeldt-Jakob disease in Australian blood donors: estimation of risk and the impact of deferral strategies

BACKGROUND AND OBJECTIVES

In Australia, a policy of deferring donors who have lived in the UK for longer than 6 months between 1980 and 1996 has been instituted to reduce the theoretical risk of transmitting variant Creutzfeldt-Jakob disease (vCJD) through the blood supply. The objective of this report was to refine estimates of the possible risks and benefits of donor-deferral strategies that are aimed at avoiding transmission of vCJD.

MATERIALS AND METHODS

Estimates of the effect of donor deferral on the blood supply in Australia were based on a 1998 survey of blood donors. The number of donations from donors potentially infected with vCJD and excluded by donor deferral was estimated based on published estimates of the size of the vCJD epidemic in the UK and assuming that the risk of vCJD in Australian blood donors was proportional to the time lived in the UK between 1980 and 1996. The possible increased number of blood donations that were infected with human immunodeficiency virus (HIV), hepatitis C virus (HCV) or hepatitis B virus (HBV) and made during a window period (as a result of increased donations from first-time donors) was estimated using published methods.

RESULTS

A strategy of deferring donations in Australia from people who have lived in the UK for 6 months or longer, between 1980 and 1996, was estimated to result in exclusion of 5.3% of all blood donations, corresponding to 50 100 donations in 1998. It was estimated that the annual number of blood donations made by donors potentially infected with vCJD is 1.15 (range 0.02--31.1, based on the uncertainty in the UK prevalence estimate). Donor deferral was estimated to remove 0.92 (range 0.02--25.1) of these donations. Replacement of 33%, 50% and 100% of excluded donations by donations from first-time donors, was estimated to result in an increase of 0.0010, 0.0019 and 0.0044, respectively, of HIV-infected donations per year donated during the window period; in an increase of 0.021, 0.038 and 0.089, respectively, of HCV-infected donations per year; and in an increase of 0.18, 0.33 and 0.76, respectively, of HBV-infected donations per year.

CONCLUSIONS

The large uncertainties involved in these analyses mean that estimates must be interpreted cautiously, but the data does suggest that donor deferral may exclude more donations from donors potentially infected with vCJD than the corresponding increase, caused by donor replacement, of window-period donations possibly infected with HIV, HCV or HBV.