The prevalence of occult hepatitis B infection among the blood donors in a donation center in Beijing

Occult HBV infection (OBI) remains a potential threat for blood safety. The prevalence of OBI was investigated in a blood donation center of Chinese PLA General Hospital to improve HBV blood safety. 229446 samples from blood donors were screened by two different enzyme-linked immunosorbent assay (ELISA) kits. 78 samples were HBV DNA positive among 212134 ELISA nonreactive donor samples. The prevalence of OBI was 0.04% (76/212134). Ten samples of OBI were permitted by the donors' content for further research, and all of these were below 200IU/mL, and six of these were below 20IU/mL(6/10,60%). Genotype B and genotype C was 20% (2/10) and 80% (8/10), respectively. 16 amino acid mutations were detected in the S region of OBI, included three mutations in MHR region of S. The prevalence of OBI is rare in this donation center. These mutations we found may contribute to the multifactorial occurrence of OBI.

Biomarkers of transfusion transmitted occult hepatitis B virus infection: Where are we and what next?

Blood transfusion is a vital procedure, where transfusion-transmitted infection of hepatitis B virus (HBV) remains an important issue, especially from blood donors with occult hepatitis B virus infection (OBI). Occult hepatitis B virus infection is a complex entity to detect using surrogate blood biomarkers for intrahepatic viral transcriptional activity, requiring a continually refined battery of tests utilised for screening. This review aims to critically evaluate the latest advances in the current blood biomarkers to guide the identification of OBI donors and discuss novel HBV markers that could be introduced in future diagnostic practice. Challenges in detecting low HBV surface antigen levels, mutants, and complexes necessitate ultrasensitive multivalent dissociation assays, whilst HBV DNA testing requires improved sensitivity but worsens inaccessibility. Anti-core antibody assays defer almost all potentially infectious donations but have low specificity, and titres of anti-surface antibodies that prevent infectivity are poorly defined with suboptimal sensitivity. The challenges associated with these traditional blood HBV markers create an urgent need for alternative biomarkers that would help us better understand the OBI. Emerging viral biomarkers, such as pre-genomic RNA and HBV core-related antigen, immunological HBV biomarkers of T-cell reactivity and cytokine levels, and host biomarkers of microRNA and human leucocyte antigen molecules, present potential advances to gauge intrahepatic activity more accurately. Further studies on these markers may uncover an optimal diagnostic algorithm for OBI using quantification of various novel and traditional blood HBV markers. Addressing critical knowledge gaps identified in this review would decrease the residual risk of transfusion-transmitted HBV infection without compromising the sustainability of blood supplies.

Efficacy of combined HBsAg, anti-HBc and anti-HBs screening in minimizing transfusion transmission risk of hepatitis B infection in low resource setting

Background

Hepatitis B Virus (HBV), and occult Hepatitis B in particular, is a major concern in the transfusion scenario, especially in endemic countries. This study attempted to estimate the prevalence of occult Hepatitis B infection (OBI) among voluntary blood donors in Maharashtra and to evaluate the role of combined screening strategy with implications in minimizing the current transfusion risks of seropositive OBI.

Methods

Donor samples were collected from 80 eligible blood banks from various districts of Maharashtra between 2014 and 2017. ELISA based screening of HBsAg, anti-HBc (total and IgM), anti-HBs titres. Real-time quantitative PCR for Hepatitis B Virus DNA (HBV DNA) were performed for all HBsAg and or anti-HBc positive samples.

Results

Out of 2398 samples tested, 20 (0.83%) samples were positive for HBsAg, whereas 547 (22.81%) were positive for anti-HBc. Out of 547 samples, 16 (2.92%) were positive for HBV DNA with median level at 247.89 IU/mL (IQR: 126.05-666.67 IU/mL). Anti-HBs levels were positive in 35.83% of OBI cases. ROC curve analysis showed that combined HBsAg, anti-HBc and anti-HBs (>50 mIU/mL) screening can more efficiently detect HBV infection in blood donors than HBsAg alone.

Conclusions

A combined HBsAg, anti-HBc and anti-HBs screening for donor samples could be an alternative achievable strategy to minimize the HBV transmission as well as financial burden. In resource limited setup, the proposed combined strategy could be helpful in minimizing the risk of OBI transmission.

Evaluating the cost-effectiveness of low-level HBV DNA screening in occult hepatitis B infection donors: A study from Shandong Blood Center, China

OBJECTIVE

This study aimed to assess the efficacy of individual-donation nucleic acid testing (ID-NAT) in detecting occult hepatitis B virus infection (OBI) among anti-HBc positive blood donors, compared to minipool nucleic acid testing (MP-NAT).

METHODS

The present study analyzed data from the Shandong Blood Center in China during the period from January 2018 to June 2022, where HBsAg-negative blood donors were screened using the 6-sample minipool nucleic acid testing (6-sample MP NAT) method. NAT-positive samples underwent subsequent anti-HBc and anti-HBs testing. Approximately 5000 samples that passed the nucleic acid mixing test were randomly selected for anti-HBc testing, and over 100 anti-HBc positive samples underwent individual donor nucleic acid testing (ID-NAT). Any HBV DNA positive samples detected by ID-NAT were subsequently confirmed using alternative nucleic acid testing methods.

RESULTS

Among 220,445 HBsAg-negative blood donors, the positivity rate of HBV DNA detection using the 6-sample minipool nucleic acid testing (MP NAT) method was found to be 0.031% (69/220,445). Of the 67 HBV DNA positive samples, 55 (82.09%) and 25 (37.31%) were found to be positive for anti-HBc and anti-HBs, respectively, using the supplementary chemiluminescent microparticle immunoassay (CMIA). Among the 4797 HBsAg-negative/MP NAT-negative samples, 909 (18.95%) tested positive for anti-HBc. Further NAT testing was performed on 164 arbitrarily selected anti-HBc-positive/MP HBV DNA-negative samples, revealing a HBV DNA positivity rate of 1.22% (2/164).

CONCLUSION

Using individual donation nucleic acid testing can significantly increase the detection rate of occult hepatitis B virus infection in anti-HBc-positive blood donors, resulting in a detection rate of 0.22% (1.22 × 0.1895). This rate is 8.10 times higher than the detection rate achieved by mixed testing methods (0.031%) [calculated as (0.22 + 0.031)/0.031]. Therefore, it is recommended to perform single HBV DNA testing on anti-HBc-positive blood donors, discard plasma with weakly positive or negative anti-HBs but positive anti-HBc, or avoid transfusing anti-HBc-positive plasma to recipients with weakly positive or negative anti-HBs to prevent HBV infection.

The high prevalence of occult hepatitis B infections among the partners of chronically infected HBV blood donors emphasizes the potential residual risk to blood safety

A small percentage of couples who regularly donated blood in China tested positive for HBsAg. Although it is well known that blood donors can acquire hepatitis B virus (HBV) infection from a chronically infected sexual partner, the prevalence of occult hepatitis B infections (OBIs) among blood donations from partners of HBV-infected chronically infected spouses and the risk to blood safety remain poorly understood. Among 212 763 blood donors, 54 pairs of couples (108 donations) were enrolled because one partner tested positive for HBsAg. Several molecular and serological examinations were conducted. The origin of HBV transmission between sexual partners was investigated further. Also evaluated was the potential risk of HBV infection with OBIs. We identified 10 (10/54, 18.6%) sexual partners of chronically infected HBV donors who were positive for HBV DNA, including five samples (9.3%) with OBIs, of which 3 (3/54, 5.6%, 1 in 70 921 donations) passed the routine blood screening tests. Seven of the 10 HBV-DNA-positive couples contracted the virus possibly through sexual or close contact. Among infected couples, immune escape mutations were observed. A high prevalence of OBIs was found among the partners of chronically infected HBV blood donors, posing a potential threat to blood safety.

Re-Entry Evaluation of Chinese Blood Donors with Unconfirmed Hepatitis B Screening Results

The hepatitis B virus (HBV) remains a high priority for Chinese blood banks due to the high prevalence of infection. HBV blood safety has been significantly improved by the implementation of highly sensitive and specific serological and molecular HBV screening assays. The multiplication of viral markers tested and the ever-increasing analytical sensitivity of the tests can make the interpretation of the results difficult. False-positive or indeterminate results may lead to permanent donor deferrals and conflicts between donors and blood banks. To avoid blood shortages, blood services aim to limit unnecessary donor losses by developing procedures for the re-entry of donors temporarily deferred due to an unconfirmed HBV reactivity. The development of such procedures based on donor follow-up and HBV confirmation remains limited. A review of the scarce data available revealed considerable heterogeneity in testing methods and re-entry algorithms, limited validation studies, and a lack of accurate assessment of the residual infectious risk potentially associated with donor re-entry. In conclusion, systematic and widely validated confirmatory testing and prolonged follow-up are essential for safe re-entry of temporary deferred donors. Standardization of HBV testing methods and the establishment of dedicated expert laboratories are needed because of the complexity of HBV infection in blood donors.

Insights on 21 Years of HBV Surveillance in Blood Donors in France

Hepatitis B virus (HBV) infection is the most frequent viral infection found in blood donors (BDs) in France. We analyzed the epidemiological and sero-molecular data on HBV infection gathered over the past two decades by the French haemovigilance surveillance network, blood screening laboratories, and the national reference center for transfusion infectious risks (NRC). Between 2000 and 2020, 6149 of the 58,160,984 donations (1.06/10,000) tested HBV positive, 98% of them from first-time blood donors (FTBDs). In addition, 2212 (0.0071%) of the 30,977,753 donations screened for HBV DNA tested DNA positive, of which 25 (1.1%) were positive only for this marker. HBV prevalence decreased by 2.8-fold and the residual risk for transfusion-transmitted HBV infection decreased 13-fold and was divided by 13. The major risk factor for HBV infection was the origin of donors (endemic country, 66.5%), followed by parenteral exposure (10.7%). In the whole HBV-positive BD population, genotype D was predominant (41.8%), followed by genotypes A (26.2%) and E (20.4%), reflecting the geographical origin of donors. The low and decreasing prevalence and incidence of HBV infection in French BDs, coupled with a screening strategy using three HBV markers (HBsAg, anti-HBc and DNA), ensures a high level of blood safety, further reinforced by the implementation of pathogen-reduction measures.

Prevalence of Occult Hepatitis B Virus Infection in Blood Donors with Negative ID-NAT in Switzerland

Introduction

Screening of hepatitis B surface antigen (HBsAg) and individual-donation nucleic acid amplification testing (ID-NAT) of blood donors have become standard to detect hepatitis B virus (HBV) infection. However, there is still a residual risk of HBV transmission by blood components of donors suffering from occult HBV infection (OBI). Therefore, many countries implemented universal testing of anti-HBV core antigen (anti-HBc) antibodies in order to increase blood safety. In Switzerland, anti-HBc testing is not part of the routine blood donor-screening repertoire. Therefore, we sought to assess prevalence of donors with OBI in a Swiss blood donor collective.

Methods

Blood donations were prospectively investigated for the presence of anti-HBc antibodies during two time periods (I: all donors, March 2017; II: first-time donors only, April 2017 until February 2018). Anti-HBc-positive findings were confirmed by an anti-HBc neutralization test. Discarded plasma samples of anti-HBc-confirmed positive donors were ultracentrifuged and subsequently retested by regular HBV-ID-NAT to search for traces of HBV.

Results

During time period I, 78 (1.6%) individuals out of 4,923 donors were confirmed anti-HBc-positive. Sixty-nine (88%) anti-HBc-positive samples were available and processed by ultracentrifugation followed by repeat HBV-ID-NAT. Four samples (5.8%) were found positive for HBV DNA. Sixty-five (94.2%) samples remained HBV NAT-negative upon ultracentrifugation. During time period II, 56 (0.9%) donor samples out of 6,509 exhibited anti-HBc-confirmed positive. Fifty-five (98%) samples could be reassessed by HBV-ID-NAT upon ultracentrifugation. Three (5.5%) samples contained HBV DNA and 52 (94.5%) samples remained HBV NAT-negative.

Conclusion

Overall, we detected 7 viremic OBI carriers among 11,432 blood donors, which tested negative for HBV by standard HBV-ID-NAT and HBsAg screening. In contrast, OBI carriers showed positive anti-HBc findings which could be confirmed in 83.8% of the cases. Thus, OBI might be missed by the current HBV screening process of Swiss blood donors. We suggest to review current HBV screening algorithm. Extended donor screening by anti-HBc testing may unmask OBI carriers and contribute to blood safety for the recipient of blood products.

Residual risk of transfusion-transmitted hepatitis B virus (TT-HBV) infection by NAT-screened blood components: A review of observed versus modeled infectivity from donors with window period and occult HBV infections

BACKGROUND

The residual transfusion-transmitted hepatitis B virus (TT-HBV) risk with different testing strategies depends on the sensitivity of screening assays, the prevalence of hepatitis B surface antigen (HBsAg) compared to HBV-DNA in window period (WP) and occult HBV infections (OBIs), and infectivity of blood in these infection stages. We compared modeled WP and OBI transmission risk in a multiregional individual donation nucleic acid amplification technology (ID-NAT) screening study with observed TT-HBV infection rates in several lookback studies.

STUDY DESIGN AND METHODS

The WP and OBI risk was estimated from ID-NAT screening data in six geographic regions. The 50% infectious dose (ID₅₀ ), a key factor in the applied risk models, was assumed to be 100-fold higher in OBI than in WP blood. The relative proportion of WP and OBI TT-risk was estimated for different screening scenarios and expressed as a percentage of the ID-NAT yield rate to allow for comparison with observed TT-rates in lookback studies.

RESULTS

Despite sevenfold to eightfold higher HBV ID-NAT yield rates in OBI than WP in South-East Asia and Europe, our models predicted that 40 (26-55)% of total residual TT-HBV risk was due to OBI, comparable to 37% observed in a Japanese hemovigilance study. Modeled TT-OBI risk was approximately 10-fold higher than observed rates of 2%-8% in five lookback studies but comparable to one other study (36%).

CONCLUSION

Although the observed TT-OBI rate was generally lower than the modeled risk, the relative risk of WP versus OBI transmission was not incompatible with the observational infectivity data. This supports the validity of our assumptions in the infectivity-based models for estimating worst-case residual risk with different testing scenarios.

High Frequency Occult Hepatitis B Virus Infection Detected in Non-Resolved Donations Suggests the Requirement of Anti-HBc Test in Blood Donors in Southern China

Background

Most Chinese Blood Centers adopted mini pool (MP) nucleic acid testing (NAT) for HBV screening due to high cost of Individual donation (ID) NAT, and different proportions of MP-reactive but ID-non-reactive donations (MP+/ID-, defined as non-resolved donations) have been observed during daily donor screening process. Some of these non-resolved donations are occult HBV infections (OBIs), which pose potential risk of HBV transmission if they are not deferred. This study is aimed to further analyze these non-resolved donations.

Methods

The non-resolved plasma samples were further analyzed by serological tests and various HBV DNA amplification assays including quantitative PCR (qPCR) and nested PCR amplifying the basic core and pre-core promoter regions (BCP/PC; 295 base pairs) and HBsAg (S) region (496 base pairs). Molecular characterizations of HBV DNA+ non-resolved samples were determined by sequencing analysis.

Results

Of 17,226 MPs from 103,356 seronegative blood donations, 98 MPs were detected reactive for HBV. Fifty-six out of these 98 (57.1%) reactive MPs were resolved as HBV DNA+, but the remaining 42 pools (42.9%, 252 donations) were left non-resolved with a high rate (53.2%) of anti-HBc+. Surprisingly, among 42 non-resolved MPs, 17 contained one donation identified as OBIs by alternative NAT assays. Sequence analysis on HBV DNAs extracted from these OBI donations showed some key mutations in the S region that may lead to failure in HBsAg detection and vaccine escape.

Conclusion

A total of 53.2% of the non-resolved donations were anti-HBc+, and OBIs were identified in 40.5% of these non-resolved pools. Therefore, non-resolved donations with anti-HBc+ might pose potential risk for HBV transmission. Our present analysis indicates that anti-HBc testing in non-resolved donations should be used to identify OBIs in order to further increase blood safety in China.

Hepatitis B infections among blood donors in England between 2009 and 2018: Is an occult hepatitis B infection a risk for blood safety?

INTRODUCTION

Hepatitis B virus (HBV) is one of the most frequent infections identified in blood donors in England and represents an ongoing blood safety risk. We have analyzed markers of HBV infections in blood donors in England between 2009 and 2018 and used these to estimate the likelihood of non-detection of occult HBV infection (OBI).

METHODS

We collected epidemiological, virological, and genotyping information on HBV cases identified in England, 2009-2018. The estimated risk of non-detection and likely transmission of OBI were compared to lookback and transfusion-transmitted infections surveillance data.

RESULTS

Six-hundered and fifty-five HBV-infected blood donors were identified in England during the 10-year period; 598 chronic, 32 acute, and 25 occult HBV infections. However, most donors with chronic and occult infections were born in Eastern Europe, Africa, or Asia (451/544, 83% and 14/24, 58%); acute infections were largely seen in UK-born donors (19/28, 68%). Genotyping of 266 HBV-positive samples revealed five genotypes (A-E), reflecting ethnicity and country of birth. Most OBIs were identified in repeat donors (19/25); lookback data identified a transmission rate of 8.3%. It is estimated that at least 13 potentially infectious donations from donors with OBI remain undetected annually, equating to an overall residual transmission risk of 3.1 per million donations using our current screening strategy of HBsAg screening with HBV nucleic acid testing (NAT) in pools of 24.

CONCLUSIONS

OBI accounted for the majority of the HBV residual risk in England. Further cost-benefit analysis is required to estimate if our current HBV screening strategy should be changed.

Blood donor screening in the Netherlands: Universal anti-HBc screening in combination with HBV nucleic acid amplification testing may allow discontinuation of hepatitis B virus antigen testing

BACKGROUND

In the Netherlands, blood donor screening for hepatitis B virus (HBV) consists of HBsAg screening since the 1970s, HBV DNA minipool testing (MP-NAT) since 2008, and anti-HBc screening since 2011. Anti-HBc reactivity causes deferral only if anti-HBs titers are <200 IU/mL, or when anti-HBc was acquired during follow-up.

STUDY DESIGN AND METHODS

Over 5.5 million donations from 582,459 Dutch donors were screened for HBV DNA, HBsAg, anti-HBc, and, if anti-HBc positive, also for anti-HBs. The added value, expressed as the yield of (potentially) infectious and/or recent HBV infections versus unnecessary donor loss, was evaluated for each of the three HBV screening tests.

RESULTS

HBV donor screening identified 89 HBV-infected donors with at least two reactive HBV markers (MP-NAT, HBsAg and/or anti-HBc). Single HBV-marker yield was: 5 MP-NAT-only, 0 HBsAg-only, and 20 anti-HBc-only donors. In addition, anti-HBc screening yielded 1,067 potentially infectious donors at risk for occult HBV infection (OBI). In total, 4,126 (0.71%) donors were anti-HBc-reactive at first-time screening, and 1,098 (0.19%) seroconverted during follow-up. Anti-HBc-related donor loss was limited to 2,627 (0.45%) donors using anti-HBs titers and two-strike programs. Donor loss due to MP-NAT and HBsAg screening was extremely low: 0 and 128 donors, respectively.

CONCLUSION

HBV donor screening could be limited to MP-NAT and anti-HBc screening. MP-NAT and anti-HBc improved blood safety by intercepting infectious donations from donors with recent infection or OBI, while HBsAg did not. Unnecessary donor loss related to anti-HBc screening is substantial but does not endanger the continuity of the blood supply.

Occult and active hepatitis B virus detection in donated blood in São Paulo, Brazil

BACKGROUND

The present study determined the HBV antigen, antibody, and DNA status in blood donations deemed to be HBV positive. Individuals with an occult HBV infection (OBI), defined as being positive for HBV DNA but negative for HBV surface antigen (HBsAg), as well as those with active infection (HBsAg-positive), were identified and characterized.

STUDY DESIGN AND METHODS

From a total pool if 198,363 blood donations, we evaluated in a cross-sectional study, 1106 samples that were positive in screening tests for antibody to HBV core antigen (HBcAb), HBsAg, and/or HBV DNA by nucleic acid testing (NAT-HBV). The presence of genetic variants in the HBV pol/S gene in individuals with an active HBV infection was also determined.

RESULTS

OBIs were detected in six of 976 samples (0.6%) that were positive only for HBcAb. The rate of HBV active infection was 0.024% (48/198,363) and there was a predominance of HBV sub-genotype A1 (62.2%, 28/45), followed by D3 (17.8%, 8/45). Mutations in the S gene were found in 57.8% (26/45) and immune escape mutations in 37.8% (17/45) of active HBV-infected donors. Among them, T123N, G145A, and D144G high-impact immune escape mutations were identified.

CONCLUSION

Highly sensitive molecular tests improve the capacity to detect OBIs. When NAT is performed in pooled samples, HBcAb test has value in the detection of donors with OBI and improves transfusion safety. Mutations in the S gene are frequent in HBsAg-positive blood, including those associated with diagnostic failure and vaccine escape mutations.

Occult hepatitis B infection and hepatocellular carcinoma: Epidemiology, virology, hepatocarcinogenesis and clinical significance

Occult hepatitis B infection (OBI) refers to a condition where replication-competent HBV DNA is present in the liver, with or without HBV DNA in the blood, in individuals with serum HBsAg negativity assessed by currently available assays. The episomal covalently closed circular DNA (cccDNA) in OBI is in a low replicative state. Viral gene expression is mediated by epigenetic control of HBV transcription, including the HBV CpG island methylation pathway and post-translational modification of cccDNA-bound histone, with a different pattern from patients with chronic HBV infection. The prevalence of OBI varies tremendously across patient populations owing to numerous factors, such as geographic location, assay characteristics, host immune response, coinfection with other viruses, and vaccination status. Apart from the risk of viral reactivation upon immunosuppression and the risk of transmission of HBV, OBI has been implicated in hepatocellular carcinoma (HCC) development in patients with chronic HCV infection, those with cryptogenic or known liver disease, and in patients with HBsAg seroclearance after chronic HBV infection. An increasing number of prospective studies and meta-analyses have reported a higher incidence of HCC in patients with HCV and OBI, as well as more advanced tumour histological grades and earlier age of HCC diagnosis, compared with patients without OBI. The proposed pathogenetic mechanisms of OBI-related HCC include the influence of HBV DNA integration on the hepatocyte cell cycle, the production of pro-oncogenic proteins (HBx protein and mutated surface proteins), and persistent low-grade necroinflammation (contributing to the development of fibrosis and cirrhosis). There remain uncertainties about exactly how, and in what order, these mechanisms drive the development of tumours in patients with OBI.

Comprehensive analysis of hepatitis B virus infections in blood donors in southern China that are surface antigen positive but nucleic acid testing negative

BACKGROUND

Hepatitis B virus (HBV) infection is one of the major concerns for the safety of blood transfusion in high-prevalent countries such as in China. Prior studies outside of China have shown hepatitis B surface antigen (HBsAg) false-reactive rate of 0.02% to 0.04%. Similarly, false-negative HBsAg and HBV DNA results may occur in infected donors. Our study analyzed HBsAg enzyme-linked immunosorbent assay (ELISA)-reactive but NAT-negative donations in Shenzhen Blood Center, China.

STUDY DESIGN AND METHODS

HBsAg ELISA-positive/NAT-negative plasma samples identified from screening 101,025 donations during 2017-2018 were analyzed by molecular and serologic tests including neutralization, chemiluminescence immunoassays, and various HBV DNA amplification assays. Molecular characterizations of HBsAg-positive/NAT-negative samples were determined by quantitative polymerase chain reaction (qPCR) and nested PCR amplification of the basic core and precore promotor regions (295 base pairs) and HBsAg (S) region (496 base pairs).

RESULTS

Screening of 101,025 eligible blood donations identified 157 (0.16%, 95% confidence interval, 0.13%-0.18%) HBsAg ELISA-positive/NAT-negative plasma samples; of those, 71 (45.2%) were HBsAg confirmed positive by further HBsAg testing and DNA positive by molecular tests with increased sensitivity. Of the 71, all but one was antibody to hepatitis B core antigen reactive without antibody to hepatitis B surface antigen, yielding one recent (window-period) HBV infection. Of the remaining donations, 80 (51%) were not considered as HBV-infected donors, and 6 (3.8%) were interpreted as indeterminate since HBsAg results were discordant with unconfirmed HBV DNA results. In the 71 confirmed positives, HBsAg levels ranged from 0.05 to 400 IU/mL and HBV DNA from 6 to 2654 IU/mL; however, the correlation between the two was weak (R² = 0.24).

CONCLUSION

Fewer than half of HBsAg ELISA-positive/NAT-negative samples were confirmed as HBsAg positive. Our study demonstrates that in highly HBV-endemic countries, assays with high sensitivity and specificity may be required.

Quality and safety measures in transfusion practice: The experience of eight southern/eastern Mediterranean countries

BACKGROUND AND OBJECTIVES

Blood transfusion is inherently associated with risks, and little is known regarding the available quality and safety measures in developing countries. No studies or census has been carried out, and therefore, no data on this compelling issue are available.

MATERIALS AND METHODS

Data emanating from eight Arabic eastern/southern Mediterranean countries who responded to five surveys were collected and tabulated.

RESULTS

Asepsis during phlebotomy, screening for serological and immuno-haematological parameters and appropriate storage conditions are maintained across all countries. Variations in blood component processing exist. Universal leucoreduction is systematically applied in Lebanon. Nucleic acid testing is only performed in Egypt. Aphaeresis procedure, leucoreduction and quality control for blood components are virtually inexistent in Mauritania. Written donor questionnaire is absent in Algeria and Tunisia. Most donor deferral periods for infectious agents are inconsistent with international standards.

CONCLUSION

Gaps in the processing and in the quality/safety measures applied to the manufacture of blood components are quite evident in most eastern/southern Mediterranean countries. The decision of establishing an effective collaboration network and an independent body - aside from WHO - composed of specialists that oversees all transfusion activities in these countries is certainly a crucial step towards ensuring an optimum level of blood safety.

Prevalence, incidence and residual risk of transfusion-transmitted hepatitis B virus infection in Italy from 2009 to 2018

BACKGROUND

In Italy, the use of nucleic acid testing for hepatitis B virus (HBV) in donor screening has allowed the detection of infections in the window phase, as well as the presence of occult infections which could potentially be transmitted. The aim of this study was to analyse the trends of epidemiological data focused on HBV infection in blood donors and to estimate the residual risk of transmitting HBV from both the window phase and occult infection over a 10-year period in Italy.

MATERIALS AND METHODS

Data were obtained from the Italian Haemovigilance System which includes the results of screening tests for transfusion transmissible infections. During the period of this survey (2009-2018), the molecular methods used for HBV screening were transcription-mediated amplification and polymerase chain reaction tests. Prevalence and incidence were calculated. The residual risk was estimated by applying the incidence-window period model for acute cases and a more recently reported model for estimating the risk due to occult infections.

RESULTS

A total of 17,424,535 blood donors and 30,842,794 donations were tested for HBV. Altogether, 6,250 donors tested positive for HBV markers: 4,782 (175.6×10⁵) were first time donors and 1,468 (10.0×10⁵) were repeat donors. The prevalence of HBV markers in first time donors was 275.9×10⁵ in 2009, declining to 143.6×10⁵ in 2018. The incidence of new infections was 3.37×10⁵ in 2009 and 2.17×10⁵ in 2018. The overall residual risk for HBV amounted to 1 in 2,566,854 donations calculated as the sum of risks of both acute infections in the window period (1 in 5,835,306 donations) and occult infections (1 in 4,582,270 blood units).

DISCUSSION

In Italy, the residual risk of transfusing a blood unit infected with HBV, both from window phase and occult infections, is currently very low, amounting to levels that can be considered tolerable.

Photodynamic Inactivation of Candida albicans in Blood Plasma and Whole Blood

The few approved disinfection techniques for blood derivatives promote damage in the blood components, representing risks for the transfusion receptor. Antimicrobial photodynamic therapy (aPDT) seems to be a promising approach for the photoinactivation of pathogens in blood, but only three photosensitizers (PSs) have been approved, methylene blue (MB) for plasma and riboflavin and amotosalen for plasma and platelets. In this study, the efficiency of the porphyrinic photosensitizer Tri-Py(+)-Me and of the porphyrinic formulation FORM was studied in the photoinactivation of Candida albicans in plasma and in whole blood and the results were compared to the ones obtained with the already approved PS MB. The results show that FORM and Tri-Py(+)-Me are promising PSs to inactivate C. albicans in plasma. Although in whole blood the inactivation rates obtained were higher than the ones obtained with MB, further improvements are required. None of these PSs had promoted hemolysis at the isotonic conditions when hemolysis was evaluated in whole blood and after the addition of treated plasma with these PSs to concentrates of red blood cells.

Anti-HBc prevalence among Croatian blood donors in a 14-year period (2004-2017): Assessment of trends, risks and need for implementing routine testing

OBJECTIVES

The anti-HBc prevalence over a 14-years period (2004-2017), trends, infectivity, residual risk, and need for testing in blood donors (BD) of the Croatian Institute of Transfusion Medicine were assessed.

MATERIAL AND METHODS

Anti-HBc was tested in 19,969 BD serum samples collected in 2004 (N=7561), 2013 (N=7318) and 2017 (N=5090). All serums were initially screened for HBsAg, anti-HCV, HIV Ag/Ab, and anti-TP. 2013 and 2017 samples were also tested by ID-NAT.

RESULTS

Over a 14-years period, the anti-HBc prevalence significantly decreased among Croatian BD (5.24% in 2004, 2.56% in 2013, and 1.32% in 2017). Similarly, the prevalence of anti-HBc-only profiles decreased from 0.62% in 2004, 0.25% in 2013, and 0.21% in 2017. The 4-time decreasing trend was observed in all age groups of BD from 2017 but mostly among repeat donors (5.90% to 1.38%). First-time donors showed no significant difference in anti-HBc prevalence probably due to their younger age (<29 years) and HBV vaccine status. However, similar anti-HBs carriage rates (80.56%, 87.57%, and 82.09%) were reported in anti-HBc positive donors over the study period. HBsAg and HBV DNA were not detected. No OBI infection was found in the study despite an OBI frequency of 1:10,900 donations previously reported in Croatia. A HBV decreasing residual risks of 68, 88, and 12 per million donations were estimated for years 2004, 2013, and 2017, respectively.

CONCLUSION

Anti-HBc testing is an additional measure of preventing HBV infection by transfusion. Implementation of anti-HBc testing will result in the deferral of 1.3% BD and should be supported by cost-benefit analyses.

Anti-HBc screening - is it worth the effort? Results of a 10-year surveillance programme covering more than 30 million donations in Germany

BACKGROUND AND OBJECTIVES

Antibodies to hepatitis B core antigen (anti-HBc) testing were added to hepatitis surface antigen (HBsAg) screening in Germany in 2006 to prevent hepatitis B virus (HBV) transmissions by chronically infected donors. We report the results of a national surveillance of anti-HBc-reactive and HBsAg-negative donations and assess the resulting gain in blood safety and the donor loss.

MATERIALS AND METHODS

Donations were tested for anti-HBc, and if reactive, by sensitive individual donation nucleic acid testing (ID-NAT) and for antibodies to HBsAg (anti-HBs). Data from the national anti-HBc surveillance from 2006 to 2015 determined the proportion of anti-HBc-reactive donations stratified for donor type, sex, anti-HBs concentration and NAT-positivity. Donor loss due to anti-HBc-reactive results was quantified.

RESULTS

Of 31 562 556 donations screened, 70 671 were anti-HBc reactive but HBsAg negative (0.22%). The proportion of repeat donors with these test results decreased significantly from 0.25% in 2007 to 0.08% in 2015. In the entire study period, 82 HBV-NAT-positive donations were identified. Of these, 47 donations were only identified by ID-NAT. A total of 54 203 anti-HBc-reactive units were discarded either due to possible infectiousness (NAT positive or anti-HBs concentration <100 IU/l) or because no further testing was performed.

CONCLUSION

Anti-HBc screening has improved blood safety in Germany. HBV-NAT-positive donations were identified after ID-NAT was triggered by the initial reactive anti-HBc result. The observed loss of donations was sustainable for maintaining an adequate blood supply in Germany.

Multiple HBV transfusion transmissions from undetected occult infections: revising the minimal infectious dose

OBJECTIVE

HBV infection by blood components is currently prevented in most developed countries by combining sensitive HBV surface antigen (HBsAg) assays, nucleic acid testing (NAT) and in a few of them antibodies against the HBV core antigen (anti-HBc) screening. HBV transmissions by blood components from three repeat donors tested negative for HBsAg and HBV DNA with a highly sensitive screening test (limit of detection (LOD): 3.4 IU/mL) were investigated.

DESIGN

30 of the 47 recipients of components produced from these three donors were examined. Transfusion transmission was confirmed by phylogenetic analysis of viral sequences obtained from recipients and donors following viral particle concentration.

RESULTS

9 of 31 (29%) recipients were infected: 7 infections were related to 200 mL of fresh frozen plasma and 2 infections to red blood cells containing 20 mL plasma. Transfusion transmission was confirmed by >99% identity of donor/recipient sequences in five cases, probable in three and possible in one. HBV active infection remained unsuspected for 24-57 months in three recipients. Five non-infected recipients carried anti-HBs when transfused. Six patients transfused with platelet concentrates treated with a pathogen reduction method were not infected. These data enabled to revise previous estimate of the minimal infectious dose from approximately 100 to 16 copies (or 3 IU) of HBV DNA.

CONCLUSIONS

HBV transfusion transmission from occult HBV infection carrying extremely low viral loads is related to plasma volume transfused and possibly prevented by anti-HBs. HBV blood safety could be further improved by either anti-HBc screening, HBV DNA NAT with a LOD of 0.8 copies/mL (0.15 IU/mL) or pathogen reduction of blood components.

Transfusion-Associated Lyme Disease - Although Unlikely, It Is Still a Concern Worth Considering

Even though hematogenous spread of the Lyme disease spirochete, Borrelia burgdorferi, has been well documented, and there are more than 300,000 cases per year of Lyme disease in the United States, no evidence (anecdotal or published) of transfusion-associated Lyme disease has been reported. Such a possibility would seem to exist but various factors, as discussed in this perspective, make this less likely to occur. Nonetheless, if not done already, safeguards need to be put in place at blood collection and dispensing facilities, possibly with the assistance of diagnostic microbiology and immunology laboratories, to ensure that the potential for the transfer of the Lyme disease spirochete through a blood transfusion remains a theoretical consideration rather than a real possibility.

False positive viral marker results in blood donors and their unintended consequences

False positive (FP) viral marker results in blood donors continue to pose many challenges. Informing donors of FP results and subsequent deferral can result in stress and anxiety for donors and additional complexity and workload for blood services. Donor management strategies need to balance the requirement to minimise donor anxiety and inconvenience while maintaining sufficiency of supply. Decisions about how and when to inform donors of FP results and determine deferral periods can be difficult as FP results, while often transitory, can take up to several years to resolve. Additional complexities include the interpretation of indeterminate serological confirmatory testing without detectable viral RNA or non-discriminated NAT results with concomitant anti-HBc reactivity - both may be due to FP results, but the former may also represent past infection and the later may represent occult hepatitis B infection. In this review we discuss strategies to minimise indeterminate serological confirmatory results, possible donor deferral policies and the impact on donors when notified of FP results. We also provide some new data from Australia that address the challenge of interpreting non-discriminated NAT results with concomitant anti-HBc reactivity. Ultimately, the challenge is for each blood service to develop appropriate strategies for donor management, taking into account local information and requirements.

Hepatitis B Virus Blood Screening: Need for Reappraisal of Blood Safety Measures?

Over the past decades, the risk of HBV transfusion–transmission has been steadily reduced through the recruitment of volunteer donors, the selection of donors based on risk-behavior evaluation, the development of increasingly more sensitive hepatitis B antigen (HBsAg) assays, the use of hepatitis B core antibody (anti-HBc) screening in some low-endemic countries, and the recent implementation of HBV nucleic acid testing (NAT). Despite this accumulation of blood safety measures, the desirable zero risk goal has yet to be achieved. The residual risk of HBV transfusion–transmission appears associated with the preseroconversion window period and occult HBV infection characterized by the absence of detectable HBsAg and extremely low levels of HBV DNA. Infected donations tested false-negative with serology and/or NAT still persist and derived blood components were shown to transmit the virus, although rarely. Questions regarding the apparent redundancy of some safety measures prompted debates on how to reduce the cost of HBV blood screening. In particular, accumulating data strongly suggests that HBsAg testing may add little, if any HBV risk reduction value when HBV NAT and anti-HBc screening also apply. Absence or minimal acceptable infectious risk needs to be assessed before considering discontinuing HBsAg. Nevertheless, HBsAg remains essential in high-endemic settings where anti-HBc testing cannot be implemented without compromising blood availability. HBV screening strategy should be decided according to local epidemiology, estimate of the infectious risk, and resources.

Towards pathogen inactivation of red blood cells and whole blood targeting viral DNA/RNA: design, technologies, and future prospects for developing countries

Over 110 million units of blood are collected yearly. The need for blood products is greater in developing countries, but so is the risk of contracting a transfusion-transmitted infection. Without efficient donor screening/viral testing and validated pathogen inactivation technology, the risk of transfusion-transmitted infections correlates with the infection rate of the donor population. The World Health Organization has published guidelines on good manufacturing practices in an effort to ensure a strong global standard of transfusion and blood product safety. Sub-Saharan Africa is a high-risk region for malaria, human immunodeficiency virus (HIV), hepatitis B virus and syphilis. Southeast Asia experiences high rates of hepatitis C virus. Areas with a tropical climate have an increased risk of Zika virus, Dengue virus, West Nile virus and Chikungunya, and impoverished countries face economical limitations which hinder efforts to acquire the most modern pathogen inactivation technology. These systems include Mirasol® Pathogen Reduction Technology, INTERCEPT®, and THERAFLEX®. Their procedures use a chemical and ultraviolet or visible light for pathogen inactivation and significantly decrease the threat of pathogen transmission in plasma and platelets. They are licensed for use in Europe and are used in several other countries. The current interest in the blood industry is the development of pathogen inactivation technologies that can treat whole blood (WB) and red blood cell (RBC). The Mirasol system has recently undergone phase III clinical trials for treating WB in Ghana and has demonstrated some efficacy toward malaria inactivation and low risk of adverse effects. A 2nd-generation of the INTERCEPT® S-303 system for WB is currently undergoing a phase III clinical trial. Both methodologies are applicable for WB and components derived from virally reduced WB or RBC.

Use of supplemental anti-HBc testing of donors showing non-discriminating reactive results in multiplex nucleic acid testing

BACKGROUND AND OBJECTIVES

The Korean Red Cross began nucleic acid amplification testing (NAT) for HIV and HCV in February 2005, and added HBV NAT beginning in June 2012. The current NAT system utilizes a multiplex assay for simultaneous detection of HBV DNA, HCV RNA and HIV-1 RNA. For samples that are reactive in the multiplex assay, we do specific tests for each virus. However, there have been cases of non-discriminated reactive (NDR) results which appear to be the result of non-specific reactions or cross-contamination, although some cases are considered to arise from the presence of low levels of HBV DNA due to occult hepatitis B infection.

MATERIALS AND METHODS

We examined the incidence of NDR results in previous donations of some NAT-reactive donors. Additionally, for those donors with NDR results, we performed an HBV core antibody (anti-HBc) assay.

RESULTS

From November 2015 to March 2016, there were 408 NAT-reactive donors. Of these, nineteen HBV NAT-reactive donors showed a history of NDR results in the past donations. Seven donors showed NDR results more than once. Of 771 NDR donors, 362 (47·0%) were anti-HBc reactive.

CONCLUSION

The NDR donors had a substantially higher rate of anti-HBc reactivity than other blood donors indicating that some with anti-HBc reactivity represent donors with occult HBV. Therefore, the incorporation of an anti-HBc testing for NDR donors could improve blood safety testing for the Korean Red Cross.

Occult hepatitis B infection and transfusion-transmission risk

Advances in serology and viral nucleic acid testing (NAT) over the last decades significantly reduced the risk of transfusion-transmitted hepatitis B virus (HBV). The combination of HBsAg testing and NAT efficiently prevents the majority of HBV transmission. However, a specific residual risk remains associated with extremely low viral DNA levels in blood donors with occult HBV infection (OBI) that are intermittently or not detectable even by highly sensitive individual donation (ID) NAT. Studies have reported HBV transfusion-transmission with blood components from donors with OBI that contained low amount of viruses (<200 virions). HBV transfusion-transmission seems to depend on a combination of several factors including the volume of plasma associated with the infected blood components transfused, the anti-HBV immune status of both recipient and donor, and possibly the viral fitness of the infecting HBV strain. Models based on clinical and experimental evidences estimate a residual transmission risk of 3-14% associated with OBI donations testing HBsAg and ID-NAT non-reactive. Anti-HBc testing has the potential to improve further blood safety but it may also compromise blood availability in settings with medium/high HBV prevalence. Pathogen reduction procedures might be considered.

Occult Hepatitis Infection in Transfusion Medicine: Screening Policy and Assessment of Current Use of Anti-HBc Testing

HBV still represents a global risk factor in transfusion medicine. The residual risk of HBV is not limited to pre-seroconversion window period but it extends to donors with occult HBV infection (OBI) characterized by the presence of HBV DNA in liver and by the absence of the virus surface antigen. Each country developed an appropriate blood screening policy according to local HBV prevalence, yields of infectious units per different screening methods and cost-effectiveness. We underline the need of maintaining a high level of attention for OBI carrier identification in all blood banks worldwide where the screening procedures are generally based on a combination of both serological markers and nucleic acid amplification test. In this context, markers such as hepatitis B surface antibodies and hepatitis B core antibodies (anti-HBc) might be useful, although the use of this latter is highly debated and still controversial. Our aim is to give an overview on the relevant diagnostic approaches for the routine screening for HBV focusing on the feasibility of anti-HBc testing as precautionary measure in preventing OBI transmission worldwide. In our tailored algorithm, the loss of about 1% of 'anti-HBc only' donors, does not significantly affect the blood supply while improving recipient safety.

An effective and potentially safe blood disinfection protocol using tetrapyrrolic photosensitizers

Aim: Conventional disinfection techniques, considered safe for plasma, are usually associated with collateral damages on concentrated platelets and erythrocytes. Alternative methods are required and antimicrobial photodynamic therapy (aPDT) seems promising. In this study the effectiveness of two photosensitizers (PS), a porphyrin and a phthalocyanine, to disinfect blood products was evaluated. Results: The cationic porphyrin was more effective in the photoinactivation of bacteria. Also, no significant osmotic stress was found for samples treated with PS at 5.0 µM in isotonic conditions after antimicrobial photodynamic therapy. Conclusion: Effective reduction of Gram-positive bacteria at 5.0 µM of PS provided promising indications toward its safe use to disinfect blood samples. For Gram-negative bacteria, lower PS concentrations, between 5.0 and 10 µM, must be tested.

Screening and diagnosis of HBV in low-income and middle-income countries

HBV testing and diagnosis of HBV-related liver disease in low-income and middle-income countries differs substantially from that in developed countries in terms of access to resources and expensive technologies requiring highly specialized staff. For identification and classification of HBV infection, genomic amplification methods to detect and quantify HBV DNA are often nonexistent or available only in central laboratories of major cities. When samples from peripheral locations do arrive, delays in receiving results generate loss to follow-up. Testing is often limited to measurement of hepatitis B surface antigen (HBsAg), alanine aminotransferase levels, aspartate aminotransferase to platelet ratio index and hepatitis B e antigen (HBeAg) to determine indications for antiviral therapy (AVT). Utilization of AVT is limited by cost and availability, particularly when patients are not covered by health insurance. The natural history of HBV infection is influenced by genotypes B and C in East Asia, where decades of immune tolerance have led to mostly vertical transmission; in sub-Saharan Africa, where genotypes A1 and E predominate, infection is transmitted horizontally between young children, followed by a nonreplicative phase. In both regions, cirrhosis and hepatocellular carcinoma are common and would be considerably ameliorated by AVT. Implementation of the HBV vaccine since the 1990s in Asia and 2000s in Africa has decreased the incidence of HBV, but vaccine failure and insufficiently effective prevention remain concerning issues.

Refining the risk estimate for transfusion-transmission of occult hepatitis B virus

BACKGROUND AND OBJECTIVES

We previously published a model to estimate the residual risk (RR) for occult hepatitis B infection (OBI) in the absence of universal anti-HBc testing. To incorporate new information on the epidemiology of OBI, we describe model refinements and estimate a more accurate HBV RR due to OBI in Australia.

MATERIALS AND METHODS

In our original model, the OBI risk, p(OBI), was defined by the rate of 'non-detection' by the HBV DNA screening test in use, p(NAT non-detection), and the average infectivity of blood components from OBI donors, p(transmission). We revised the model by integrating three refinements: that donations with anti-HBs levels of >10 IU/l, or donations solely for manufactured plasma products, be excluded from the risk calculation, and an updated estimate of p(transmission).

RESULTS

Refining our OBI RR model resulted in a more than 10-fold reduction in the reported RR risk to recipients from OBI in our donor population. Based on the use of a common data set, the mean OBI RR risk decreased from 1 in 374 354 donations (95% CI: 1 in 191 940-1 072 681) to 1 in 3 984 033 (95% CI: 1 in 1 146 188-65 268 257) for the refined model.

CONCLUSION

Our model refinements provide a more realistic measure of the HBV RR in the donor population. Unlike the previous model, the new model demonstrates that the risk of HBV due to OBI in the Australian blood donor population is negligible, and further potentially cost-ineffective risk management strategies are not currently warranted.