Infectivity of blood components with low hepatitis B virus DNA levels identified in a lookback program

Seroreactivity of antibodies to hepatitis B core antigen among hepatitis B surface antigen-screened negative blood donors and its implications for blood safety in a resource-constrained country

BACKGROUND AND OBJECTIVES

Transfusion-related hepatitis B infections have been reduced significantly with the implementation of blood screening using both serology and nucleic acid amplification technology (NAT) in developed countries. However, in resource-constrained countries, where NAT is inaccessible, the risk persists from early acute and occult cases. This study aimed to determine the antibodies to hepatitis B core antigen (anti-HBc) reactive rate among hepatitis B surface antigen (HBsAg)-screened negative blood donors and its impact on blood safety in the Philippines.

MATERIALS AND METHODS

A total of 1602 HBsAg-negative samples, randomly collected from nine leading blood service facilities representative of each region in the Philippines, were tested for anti-HBc immunoglobulin M (IgM), Total and antibodies to HBsAg (anti-HBs) using the Architect i2000SR Immunoassay Analyser (Abbott Laboratories, IL). Anti-HBc IgM and/or Total repeat reactive were further tested for hepatitis B virus (HBV) NAT using the Cobas TaqScreen MPX v2.0 (Roche Diagnostics, Basel).

RESULTS

Overall, 19.16% HBsAg-negative samples (n = 307/1602) were reactive for either anti-HBc IgM or Total or a combination of both, of which 1.3% (n = 4/307) had detectable HBV-DNA and 80.5% (n = 247/307) were anti-HBs positive. About the anti-HBs titres, 30.27% (n = 485/1602) were positive (≥10 IU/L) with 55.67% (n = 270/485) having titres ≥100 IU/L. Anti-HBs-only-positive samples were 14.85% (n = 238/1602).

CONCLUSION

We observed a high anti-HBc reactive rate (19.16%) with 3.7% anti-HBc-only reactive (anti-HBs negative) and 1.3% HBV-DNA positive. This warrants the need to reconsider existing screening practices to improve blood safety in the country.

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.

Serological and Molecular Characterization of Occult HBV Infection in Blood Donors from South Italy

Despite good vaccine coverage and careful blood donor selection policies, hepatitis B virus (HBV) is still the most frequent viral infection among blood donors (BDs) in Italy, mostly in the occult form (OBI). We studied the virological features of OBI in BDs from South Italy by serology, molecular testing for HBV-DNA, and sequencing for HBV genotypes and mutations. One hundred and two samples from 95 BDs (22.1% first time, 87.9% regular, median age 57 years) positive for HBV-DNA and negative for HBsAg were retrospectively analyzed. HBV biomarkers were detected in 96.9% (anti-HBc in 44.2%, anti-HBc plus anti-HBs in 49.5%, anti-HBs alone in 3.2%). No risk factor was declared by 45.3% of donors. HBV-DNA levels were very low (median: 7 IU/mL). All samples harbored HBV genotype D and single or multiple mutations in the S gene were found in 28/36 sequences analyzed and in 75% of donors. Mutations were unrelated to gender, donor group or serological patterns. An HBsAg assay with enhanced sensitivity was positive in samples from seven donors (7.4%), two of which negative for HBV-DNA by real-time PCR. OBI still represents a risk for HBV transmission from blood donations; screening by highly sensitive serological and molecular assays is warranted.

Marked reduction in the incidence of transfusion-transmitted hepatitis B virus infection after the introduction of antibody to hepatitis B core antigen and individual donation nucleic acid amplification screening in Japan

BACKGROUND

In Japan, 41 million blood donations have been screened for hepatitis B virus (HBV) during the past 8.4 years using individual donation nucleic acid amplification testing (ID-NAT) and antibody to hepatitis B core antigen (anti-HBc) screening.

STUDY DESIGN AND METHODS

Transfusion-transmitted HBV infection (TT-HBV) incidence was examined. Donated blood implicated in TT-HBV was analyzed for infection stage and DNA levels. Causative HBV strains were phylogenetically analyzed.

RESULTS

Among 5162 (0.013%) ID-NAT positives, window period (WP) and occult HBV infection (OBI) accounted for 3.4% (176) and 11.5% (594), respectively. No OBI-related TT-HBV occurred. Seven blood donations caused eight TT-HBV cases, six of which were in the pre-ID-NAT WP, leaving one with an unresolved infection stage. Seven cases were caused by platelet concentrate (180 mL plasma) and one case by fresh-frozen plasma (200 mL plasma), which contained estimated infectious doses varying between 2 and 2300 HBV virions. HBV subgenotypes in five cases were HBV/A2. Complete genome sequences of the transmitting A2 strains were nearly identical (99.6%-100%) and clustered in a group that included HBV/HIV-1 coinfections and a higher proportion of donors in the acute infection phase (69%) than the other group of HBV/A2 sequences (5%).

DISCUSSION

The incidence of observed TT-HBV cases has significantly reduced to 0.19 per million in the ID-NAT screening period. OBI-related TT-HBV was eliminated by anti-HBc screening. Established TT-HBV cases were caused by blood products with large plasma volumes containing extremely low HBV concentrations derived from blood donors at a very early infection stage.

Occult hepatitis B in Iranian blood donors, an overview of the challenges: A narrative review

Background

Occult hepatitis B infection (OBI) is a transfusion-transmitted infection. Although, screening the hepatitis B virus among blood donors can play an important role in increasing the health of blood products, OBI screening in blood transfusion centers is still a challenge. This review study aimed to appraise the challenges of OBI screening and its associated do's and don'ts in blood transfusion centers.

Methods

In this review study, a search was conducted on the electronic databases of PubMed, Web of Science, Scopus, Ovid, Irandoc, and Magiran from January 1996 to December 2020. Also, cross-sectional studies that determined the prevalence of OBI or anti-HBc were included in the study. In addition, studies with incomplete data on the prevalence of OBI were excluded.

Results

The prevalence of OBI varies among Iranian blood donors. The rates reported by blood transfusion centers of Mashhad, Ahvaz, and Tehran were 0%, and Isfahan, Shiraz, and Kerman were 0.9%, 0.08%, and 2.36%, respectively. In areas with high prevalence of hepatitis B virus, OBI screening only by anti-HBc test led to the exemption of blood donors from donating blood. Avoiding OBI screening also effected the risk of virus transmission to blood recipients. Plasma products had a higher risk (85%) of virus transmission.

Conclusions

Determining an appropriate screening strategy based on prevalence status, the cost-effectiveness of screening tests, and the policies of each blood transfusion center is essential.

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.

Efficacy of Different Testing Scenarios in Reducing Transfusion-Transmitted Hepatitis B Virus (TT-HBV) Infection Risk

The efficacy of different screening scenarios in reducing hepatitis B virus (HBV) transmission risk as compared to the risk without screening was modeled in 9,337,110 donations from four geographical regions that had been subjected to hepatitis B surface antigen (HBsAg) and individual donation nucleic acid amplification testing (ID-NAT). We used the Weusten models for estimating infectivity risk for Red Blood Cell (RBC) transfusions in eight HBV infection stages and then evaluated multiple screening strategies based on minipool (MP) and ID-NAT options of different sensitivity for their efficacy in reducing this risk. The efficacy in reducing HBV transmission risk by screening scenarios across the regions varied between 81% (HBsAg only) and 99.2% (ID-NAT and anti-HBc). Highly sensitive ID-NAT alone achieved a slightly higher risk reduction (97.6−99.0%) than minipool of 6 donations (MP6)-NAT in combination with HBsAg and anti-HBc (96.3−98.7%). In ID-NAT screened lapsed and repeat donors, the additional risk removed by HBsAg testing was minimal (<0.1%). The modeling outcomes in this and two previous reports using this multi-regional database suggest that one could consider an ID-NAT alone testing scenario as an alternative to MP-NAT and serology-based testing algorithms and restrict serologic testing to first-time donors only.

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.

Frequency of hepatitis B virus-DNA among hepatitis B surface-Ag negative, anti-hepatitis B core antibody-positive blood donors in Yazd, Iran

BACKGROUND:

The diagnosis of hepatitis B infection in most blood transfusion centers is based on hepatitis B surface (HBs) antigen detection by an enzyme immunoassay method. This study aimed to determine the frequency of hepatitis B core (HBc) antibody, HBs antibody, and hepatitis B virus (HBV) DNA among HBs antigen-negative healthy blood donors of Yazd province, Iran.

MATERIALS AND METHODS:

This cross-sectional study was conducted on 1500 healthy blood donor samples negative for HBs antigen, hepatitis C virus antibody, human immunodeficiency virus antigen/antibody, and rapid plasma regain tests. All samples were screened for HBc antibody test. HBs antibody and real-time polymerase chain reaction were performed for HBc antibody-positive samples.

RESULTS:

HBc antibody was positive in 74 (4.9%) samples and 11 (14.9%) of 74 positive samples for HBc antibody were negative for HBs antibody. Sixty-three (85.1%) positive samples for HBc antibody had HBs antibody titer over 10 IU/L, and 43 (58.1%) had HBs antibody titer over 100 IU/L. There was no hepatitis B DNA-positive sample in the present study.

CONCLUSIONS:

The study results suggest that there is a very low risk for transmission of HBV through blood donors of Yazd, Iran.

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.

An assessment of hepatitis B virus prevalence in South African young blood donors born after the implementation of the infant hepatitis B virus immunization program: Implications for transfusion safety

BACKGROUND

The prevalence of hepatitis B surface antigen is estimated to be 6.7% in the South African population and in April 1995 the nation introduced universal hepatitis B virus (HBV) vaccination for newborns and infants. We studied the temporal association of this program with HBV prevalence in young blood donors and the contemporary HBV incidence and residual risk of transfusion-transmitted HBV infection (TT-HBV).

METHODS

We used blood donation data from January 2011 to December 2019. Estimation of HBV prevalence donations made by first-time blood donors were analyzed by birth cohort and covariates. To estimate the incidence and residual risk of TT-HBV, mathematical models used data from both first time and repeat donors.

RESULTS

HBV prevalence in first-time donors decreased from 0.84% (95% confidence interval [CI] 0.78-0.90) in 2011 to 0.66% (95% CI 0.61-0.70) in 2019. The post-1995 birth cohort had a significantly lower HBV prevalence of 0.14% (95% CI 0.13-0.15) than the pre-1985 birth cohort of 1.29% (95% CI 1.25-1.33) and the odds of HBV infection were reduced in a multivariable model (odds ratio [OR] = 0.28, 95% CI 0.24-0.34). The residual risk of TT-HBV occurring from window-period, occult, and possible vaccine breakthrough infections were estimated at 36.9, 5.8, and 2.2 per million red blood cell transfusions, respectively.

CONCLUSION

Donors born after the start of routine HBV immunization had significantly lower prevalence of HBV infection, supporting the effectiveness of the vaccination program. The contemporary residual risk of TT-HBV has decreased and should decline further as more vaccinated young people join the donor pool.

Characteristic of HBV nucleic acid amplification testing yields from blood donors in China

BACKGROUND

Nucleic acid amplification testing (NAT) for blood screening has been previously performed in some countries to determine NAT yields. The current study sought to explore the non-discriminating reactive NAT yields using individual-NAT (ID-NAT) and characteristics of HBV NAT yields through a 10-year retrospective analysis in Zhejiang, China.

METHODS

Blood donations were analyzed using individual-NAT mode by the transcription-mediated amplification (TMA) method. Supplementary HBV serological tests were performed using chemiluminescent immunoassay, and HBV viral load assay was performed by real-time polymerase chain reaction. Follow-up studies were performed in partial donors with low HBV viral loads.

RESULTS

Non-discriminating reactive NAT yields and HBV NAT yields varied in different years. The yields ranged from 853.73 per million to 2018.68 per million and 624.60 per million to 1669.50 per million, respectively. In the 476 NAT yields, 19 were probable window periods (WP), 33 probable occult hepatitis B virus infections (OBIs), 409 were confirmed OBIs and 15 were chronic HBV infections. ID-NAT results were categorized in four groups, and the findings showed that the levels of HBV DNA viral loads were different in the four different groups (χ² = 275.02, p < 0.01). HBV viral load distribution was significantly different between anti-HBs positive and anti-HBc positive samples (χ² = 49.429, p < 0.01). Notably, only 42.03% donors were NAT repeated positive in the 138 repeat donors' follow up tests.

CONCLUSION

NAT screening of blood donations can reduce the risk of transfusion-transmitted HBV infections. Positive proportions of anti-HBs and anti-HBc are correlated with the HBV viral load level. However, low level of viral load donors pose risks in HBV NAT assays, and show fluctuating state for HBV viral load and leads to non-repeated NAT results during follow up studies.

Prolonged incubation period of hepatitis B in a recipient of a nucleic acid amplification test-negative hepatitis B virus window donation

BACKGROUND

The occurrence of transfusion-transmitted hepatitis B virus (HBV) infection has fallen dramatically due to continuous improvements in pre-transfusion laboratory testing. However, the characteristics of transfusion-transmitted HBV infection caused by individual donor nucleic acid amplification test (ID-NAT)-negative blood products are unclear.

CASE PRESENTATION

A 76-year-old woman with acute myeloid leukemia was diagnosed with transfusion-transmitted HBV infection after receiving apheresis platelets derived from an ID-NAT-negative blood donation. This case was diagnosed definitively as transfusion-mediated because complete nucleotide homology of a 1556 bp region of the HBV Pol/preS1-preS2-S genes and a 23 bp region of the HBV core promoter/precore between the donor and recipient strains was confirmed by PCR-directed sequencing. The case is uncommon with respect to the unexpectedly prolonged HBV-DNA incubation period of nearly 5 months after transfusion (previously, the longest period observed since the recent implementation of ID-NAT pre-transfusion laboratory testing in Japan was 84 days). Slow-replicating HBV genotype A2 may contribute to the prolonged incubation period; also, the quantity of apheresis platelets delivered in a large volume of plasma, and/or the immune response of the recipient suffering from a hematological neoplasm, may have contributed to establishment of HBV infection in the recipient. This was supported by analysis of three previously documented cases of transfusion-transmitted HBV infection by blood products derived from ID-NAT-negative donations in Japan.

CONCLUSION

Continuous monitoring of HBV infection for longer periods (>3 months) may be required after transfusion of blood components from an ID-NAT-negative HBV window donation.

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.

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.

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.

Prediction and clinical implications of HBV reactivation in lymphoma patients with resolved HBV infection: focus on anti-HBs and anti-HBc antibody titers

Hepatitis B virus (HBV) reactivation (HBV-R) and hepatitis related to HBV-R are well-recognized complications that occur in patients who have undergone cytotoxic chemotherapy or immunosuppressive therapy. The degree of HBV-R in this population varies from self-limited or asymptomatic hepatitis to acute liver failure, which may lead to life-threatening events. However, no established treatment or standard surveillance method exists for monitoring patients to predict the development of HBV-R during or after chemotherapy or immunosuppressive therapy, particularly regarding resolved HBV infection. Prophylactic antiviral agents and regular monitoring of HBV-DNA levels are known to be useful methods for preventing HBV-R; however, these methods require considerable financial resources, and such resources are limited in the endemic areas of HBV infection. Most patients with resolved HBV infection do not develop a hepatitis flare or self-limited HBV-R with only an increase in HBV DNA. However, some patients may develop HBV-R even 1 year or more after the last chemotherapy treatment. Therefore, predicting the development of HBV-R and its timing is difficult, and exploring markers that could help predict whether or when HBV reactivation occurs is necessary. In this review, we address the predictive risk factors for HBV-R in patients with resolved HBV infection, focusing on the ability of anti-HBs and anti-HBc to predict HBV-R. We conclude that the combination of anti-HBc and anti-HBs titers may be a reliable and useful predictor for managing HBV-R.

Optimal titer of anti-HBs in blood components derived from donors with anti-HBc

BACKGROUND

The ultimate strategy to cope with transfusion-transmitted hepatitis B virus (HBV) infection caused by transfusion of blood from donors with historical HBV infection is to reject all donors having anti-HBV core antigen (anti-HBc). However, this strategy would result in a huge loss of blood donors and subsequent blood inventory collapse. On the other hand, anti-HBc-positive blood is reportedly not infectious when containing more than 100 mIU/mL of anti-HBV surface antigen (anti-HBs).

STUDY DESIGN AND METHODS

In Japan, anti-HBc-positive blood has been used for transfusion if it contained 200 mIU/mL or more of anti-HBs. First, to verify the screening policy, clinical outcomes for transfusion of such blood were analyzed for the 2008-2012 period. Second, human hepatocyte-repopulated severe combined immunodeficiency mice were inoculated with HBV preincubated with varying doses of anti-HBs, then viremic status was followed. The effects of anti-HBs across different HBV genotypes were also investigated.

RESULTS

Twenty-three transfusion-transmitted HBV infections related to anti-HBc-positive blood components were identified. None of the blood responsible for these cases contained 200 mIU/mL or more of anti-HBs. When 100 μL of plasma containing 10⁴ copies of HBV and 20 mIU of anti-HBs was injected into severe combined immunodeficiency mice, no viremia was detected within 13 weeks. Genotype C anti-HBs was capable of total inhibition of genotype A HBV replication, whereas genotype A anti-HBs inhibited genotype C HBV to a lesser extent.

CONCLUSION

Anti-HBc-positive blood containing 200 mIU/mL or more of anti-HBs appears safe as a transfusion component. HBV vaccination seems effective between HBV genotypes A and C.

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.

Recent and occult hepatitis B virus infections among blood donors in the United States

BACKGROUND

Characteristics of US blood donors with recent (RBI) or occult (OBI) hepatitis B virus (HBV) infection are not well defined.

METHODS

Donors with RBI and OBI were identified by nucleic acid and serologic testing among 34.4 million donations during 2009-2015. Consenting donors were interviewed and their HBV S-gene sequenced.

RESULTS

The overall rate of HBV-infected donors was 7.95 per 100,000; of these, 0.35 per 100,000 and 1.70 per 100,000 were RBI and OBI, respectively. RBI (n = 120) and OBI (n = 583) donors constituted 26% of all HBV-infected (n = 2735) donors. Detection of HBV DNA in 92% of OBI donors required individual donation nucleic acid testing. Donors with OBI compared to RBI were older (mean age, 48 vs 39 years; p < 0.0001) with lower median viral loads (9 vs. 529 IU/mL; p < 0.0001). A higher proportion of OBI than RBI donors were born or resided in an endemic country (39% vs. 5%; p = 0.0078). Seventy-seven percent of all RBI and OBI donors had multiple sex partners, an HBV-risk factor. Of 40 RBI and 10 OBI donors whose S gene was sequenced, 33 (83%) and 6 (60%), respectively, carried HBV subgenotype A2; 18 (55%) and 2 (33%), respectively, shared an identical sequence. Infection with 1 or more putative HBV-immune-escape mutants was identified in 5 (50%) of OBI but no RBI donors.

CONCLUSION

RBI and OBI continue to be identified at low rates, confirming the importance of comprehensive HBV DNA screening of US blood donations. HBV-infected donors require referral for care and evaluation and contact tracing; their HBV strains may provide important information on emergent genotypes.

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.

Hemodialysis-Associated Infections

Hemodialysis patients are at increased risk of infections, which are common adverse events among this patient population. We review factors contributing to infections among hemodialysis patients and epidemiology of common infections and outbreaks, including bloodstream infections, vascular access infections, and infections caused by bloodborne pathogens. Recommendations for prevention are discussed with emphasis on essential infection control practices for hemodialysis settings.

Blood donor testing for hepatitis B virus in the United States: is there a case for continuation of hepatitis B surface antigen detection?

BACKGROUND

In the United States, blood donor testing for hepatitis B surface antigen (HBsAg) was initiated in the early 1970s. More recently, testing for antibody to hepatitis B core antigen (anti-HBc) and hepatitis B virus (HBV) DNA have been added. The incidence of hepatitis B has been declining. This study reviews the current status of testing and questions the need for continuation of HBsAg testing.

STUDY DESIGN AND METHODS

From July 2011 to June 2015, a total of 22.4 million donations were serologically tested for HBsAg and anti-HBc and for HBV-DNA by nucleic acid testing (NAT). All reactive results were evaluated and a subset of donations that were either potential NAT yield (seronegative) or serologically positive but nonreactive by HBV NAT in minipools (MPs) of 16 were further evaluated by individual donation (ID)-NAT. Samples with detectable HBV DNA were defined as actively infected and considered potentially infectious.

RESULTS

Routine testing plus supplemental ID-NAT identified 2035 samples representing active infection including 1965 with anti-HBc, 1602 with HBsAg, and 1453 with HBV DNA by MP-NAT, for respective rates per hundred-thousand donations of 9.10, 8.78, 7.16, and 6.50, continuing the downward trend previously observed. There were 29 HBV DNA-yield samples (1:771,389), 35 HBsAg-yield samples (anti-HBc nonreactive), and 404 with occult hepatitis B infection. There were six samples with HBsAg and HBV DNA detectable only by ID-NAT in the absence of anti-HBc; additional testing was consistent with extremely low or negligible levels of DNA.

CONCLUSIONS

Point estimates of HBV infection rates among blood donors continue to decline, as do those for incidence and residual risk. Elimination of HBsAg screening would have negligible impact, with a risk less than 1 per 4 million donations.

Novel monitoring of hepatitis B reactivation based on ultra-high sensitive hepatitis B surface antigen assay

BACKGROUND & AIMS

Occult hepatitis B virus (HBV) infection should be evaluated before systemic chemotherapy to prevent HBV reactivation-related hepatitis. We investigated HBV reactivation using high sensitivity HB surface antigen (HBsAg) chemiluminescent enzyme immunoassay (HBsAg-HQ) and ultra-high sensitive HBsAg assay employing a semi-automated immune complex transfer chemiluminescence enzyme technique (ICT-CLEIA).

METHODS

Of 120 HBV-resolved patients with haematological malignancy receiving systemic chemotherapy from 2012 to 2015 in our hospital, 13 patients had HBV DNA reactivation (in 12/13 patients HBV DNA became quantifiable) according to HBV DNA monitoring. These patients were applied for Architect HBsAg-QT (detection limit:50 mIU/mL), HBsAg-HQ (5 mIU/mL) and ICT-CLEIA (0.5 mIU/mL) using stored samples.

RESULTS

When HBV DNA was firstly quantifiable by regular HBV DNA monitoring, HBsAg-QT was detected in 1/12 patients (8%), HBsAg-HQ was detected in 4/12 patients (33%) and ICT-CLEIA was detected in all 12 patients (100%), suggesting that the sensitivity of ICT-CLEIA was comparable to that of HBV DNA quantification. Interestingly, two patients were HBsAg positive by ICT-CLEIA before HBV DNA became detectable. Median difference of detectable point between HBV DNA and ICT-CLEIA was zero (range from -28 to 56 days), while median delay by HBsAg-QT or HBsAg-HQ was 52.5 days after HBV DNA became detectable. Although anti-HBs titres were high (131.9 mIU, 80.4 mIU) in two patients with escape mutations (Saa126V, Saa145R), HBsAg by ICT-CLEIA and HBV DNA were detectable concurrently.

CONCLUSIONS

ICT-CLEIA is a novel assay for HBV monitoring to prevent hepatitis caused by HBV reactivation.

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.

Three-Year Experience in NAT Screening of Blood Donors for Transfusion Transmitted Viruses in Croatia

Background

Croatia implemented individual donation (ID)-NAT testing of blood donors in 2013 for three viruses HBV, HCV, and HIV-1 as a mandatory test for all blood donors. This study assessed the impact of NAT screening 3 years after its implementation.

Methods

A total of 545,463 donations were collected and screened for HBV, HCV, and HIV-1 using the Procleix Ultrio Plus Assay. All initially reactive (IR) NAT samples were retested in triplicate and, if repeatedly reactive (RR), NAT discriminatory assay (dNAT) was performed. ID-NAT positive donations were confirmed by RT-PCR on the COBAS AmpliPrep/TaqMan platform.

Results

Out of 545,463 samples tested, 108 (0.02%) were RR in NAT. There were 82 (75,9%) HBV reactive, 16 (14.8%) HCV reactive, and 10 (9.3%) HIV-1 reactive samples. 51 (47.2%) samples were ID-NAT positive only. Out of these 51 NAT yield cases, 1 window period HIV-1 and 50 occult HBV infections (OBI) were determined. There were only two potential HBV DNA transmissions from OBI donors.

Conclusion

The implementation of NAT screening for three viruses has improved blood safety in Croatia. During the 3-year period, 1 window period HIV-1 and a number of occult HBV donations were identified.

Usefulness of nucleic acid testing to reduce risk of hepatitis B virus transfusion-transmitted infection in Argentina: high rate of recent infections

BACKGROUND

Results from 10-year experience using nucleic acid test (NAT) screening in a blood bank of Córdoba are presented, showing the first data on prevalence of recent hepatitis B virus (HBV) infections and occult HBV infections (OBIs) in Argentina.

STUDY DESIGN AND METHODS

Molecular screening was performed by COBAS AmpliScreen human immunodeficiency virus Type 1 (HIV-1) test Version 1.5 and COBAS AmpliScreen hepatitis C virus (HCV) test Version 2.0 and COBAS TaqScreen MPX and MPX Version 2.0 test (Roche Molecular Systems). To characterize OBI, additional molecular and serologic assays were performed.

RESULTS

As results of NAT, 0.075% of the donors (155/205,388) tested positive for HIV, 0.05% (106/205,388) for HCV, and 0.045% (76/168,215) for HBV. Donors who tested positive for HIV or HCV by NAT were also positive by serology. There was one of 33,643 donors recently infected with HBV. At time of donation, six of 76 (7.9%) donors with confirmed HBV infection presented virologic and serologic profiles consistent with OBI. By additional studies three were OBI, two were window period infections, and one remained unclassified.

CONCLUSION

NAT contributed significantly to the reduction of the potential risk of HBV transmission with a frequency of one in 56,072, detecting three in 168,215 donors without serologic evidence of infection. NAT also detected three in 168,215 OBIs. The finding of high frequency of recent infections (1/33,643), unexpected for this country, highlights the need of promoting unified effective regulations that enforce the use of NAT in all blood banks in Argentina and points out the importance of assessing the risk of HBV transmission in blood banks of other countries considered to be low-endemic.

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.

Quantification of Transfusion Recipients at Risk of Receiving Hepatitis B Virus-Contaminated Blood Components: A Korean Study

Although there are lots of studies about the risk for the hepatitis B virus infection such as the residual risk for donated blood, there is no research on the risk of HBV infection, from the viewpoint of recipients in Korea. Using the data about HBsAg status of donated blood in 2008 and 2009, the distribution of blood components from the claim data of health insurance in 2009, the distribution of HBsAg and HBsAb of recipients, and some assumptions, we quantified the number of recipients in Korea that might be expected to receive HBV-contaminated blood components, as a proxy index for HBV infection by transfusion in 2009. Of the 376,211 recipients, the number who might be expected to receive blood components with HBV in 2009 was 23.2 (95 % CI 13.6, 36.8) in the basic model, 43.2 (95 % CI 25.4, 68.7) in extended model I, 55.2 (95 % CI 32.5, 87.7) in extended model II and 101.6 (95 % CI 59.8, 161.4) in extended model III. The number of HBV-positive samples per 100,000 transfused units was 0.6 in the basic model (95 % CI 0.3, 0.9), 1.1 in extended model I (95 % CI 0.6, 1.8), 1.4 in extended model II (95 % CI 0.8, 2.2), and 2.6 in extended model III (95 % CI 1.5, 4.1). This study showed that a few recipients might receive HBV-contaminated blood component by transfusion. These results could be used as a scientific evidence for health policy on HBV transfusion infection.

Occult Hepatitis B virus infection in previously screened, blood donors in Ile-Ife, Nigeria: implications for blood transfusion and stem cell transplantation

BACKGROUND

Hepatitis B virus (HBV) transmission through blood transfusion is reduced by screening for hepatitis B surface antigen (HBsAg). However this method cannot detect the presence of occult hepatitis B virus infection. This study sought to determine the prevalence of occult hepatitis B virus infection among blood donors in Ile-Ife, Nigeria. For the first time in Nigeria we employed an automated real-time PCR- method to investigate the prevalence of occult HBV in blood donors.

METHODS

Blood donors screened with HBsAg immunochromatographic rapid test kits at the blood transfusion units of two hospitals and found to be negative were recruited into the study. Questionnaires to elicit risk factors for HBV infection were administered and then 10 ml of blood was collected from each donor. Plasma samples obtained from these HBsAg negative blood donors were screened again for HBsAg using an enzyme-linked immunosorbent assay (ELISA) method, and those found negative were screened for the presence of total antibody to the HBV core antigen (anti-HBc) using ELISA method. Those positive to anti-HBc were then tested for HBV DNA, using an automated real-time PCR method.

RESULTS

Five hundred and seven blood donors found HBsAg negative by immunochromatographic rapid test kits at both blood transfusion units, were tested for HBsAg using ELISA and 5 (1 %) were HBsAg positive. The 502 found negative were tested for anti-HBc and 354 (70.5 %) were found positive implying previous exposure to HBV and 19 (5.4 %) of the 354 anti-HBc positive had HBV DNA signifying occult HBV infection. No risk factors were found to be associated with the presence of HBV DNA among those who tested positive.

CONCLUSION

Occult HBV infection exists in blood donors in Ile-Ife, Nigeria and the use of HBsAg alone for screening prospective donors will not eliminate the risk of HBV transmission in blood transfusion or stem cell transplantation.

Prevalence of occult hepatitis B infection in patients visiting tertiary care hospital

BACKGROUND

To study the prevalence of occult hepatitis B virus infection (OBI) in a tertiary care hospital.

METHODS

50 HBsAg negative individuals, each amongst blood donors, alcohol dependence syndrome (ADS), alcoholic cirrhotics, hepatitis C virus (HCV)/cryptogenic cirrhotics, end-stage renal disease (ESRD) on maintenance haemodialysis for one year, all malignancies prior to chemotherapy and HIV positive patients were evaluated for anti-HBc total antibody, and blood hepatitis B virus (HBV) DNA amplification in those tested positive.

RESULTS

A total of 60/369 (16.2%) individuals were anti-HBc total positive, 13/50 (26%) of HCV/cryptogenic cirrhotics, 13/52 (25%) of HIV positive, 10/50 (20%) of patients with malignancy, 10/51 (19.6%) and 7/59 (11.9%) of alcoholic cirrhotics and ADS respectively had intermediate prevalence, while, blood donors 5/55 (9.1%), ESRD patients 2/52 (3.8%) had low prevalence. 12 patients (20% of all anti-HBc total positive cases) were HBV DNA positive, 5 HCV cirrhotics (10% of total HCV/cryptogenic), 4 HIV positive (7.69%), 1 each of ADS (1.69%), alcoholic cirrhotics (1.96%) and malignancy group (2%). Blood donors and ESRD patients were negative for HBV DNA.

CONCLUSION

HBV DNA amplification may under diagnose OBI and anti-HBc total positivity may be a better surrogate marker. Nucleic acid testing of blood donors, however is preferred, especially in high endemic areas. OBI must be looked for in cirrhotics, HIV infection, and patients with cancers prior to chemotherapy, as they may contribute to morbidity in them.

Genetic variation of occult hepatitis B virus infection

Occult hepatitis B virus infection (OBI), characterized as the persistence of hepatitis B virus (HBV) surface antigen (HBsAg) seronegativity and low viral load in blood or liver, is a special form of HBV infection. OBI may be related mainly to mutations in the HBV genome, although the underlying mechanism of it remains to be clarified. Mutations especially within the immunodominant “α” determinant of S protein are “hot spots” that could contribute to the occurrence of OBI via affecting antigenicity and immunogenicity of HBsAg or replication and secretion of virion. Clinical reports account for a large proportion of previous studies on OBI, while functional analyses, especially those based on full-length HBV genome, are rare.

Asian-Pacific clinical practice guidelines on the management of hepatitis B: a 2015 update

Worldwide, some 240 million people have chronic hepatitis B virus (HBV), with the highest rates of infection in Africa and Asia. Our understanding of the natural history of HBV infection and the potential for therapy of the resultant disease is continuously improving. New data have become available since the previous APASL guidelines for management of HBV infection were published in 2012. The objective of this manuscript is to update the recommendations for the optimal management of chronic HBV infection. The 2015 guidelines were developed by a panel of Asian experts chosen by the APASL. The clinical practice guidelines are based on evidence from existing publications or, if evidence was unavailable, on the experts' personal experience and opinion after deliberations. Manuscripts and abstracts of important meetings published through January 2015 have been evaluated. This guideline covers the full spectrum of care of patients infected with hepatitis B, including new terminology, natural history, screening, vaccination, counseling, diagnosis, assessment of the stage of liver disease, the indications, timing, choice and duration of single or combination of antiviral drugs, screening for HCC, management in special situations like childhood, pregnancy, coinfections, renal impairment and pre- and post-liver transplant, and policy guidelines. However, areas of uncertainty still exist, and clinicians, patients, and public health authorities must therefore continue to make choices on the basis of the evolving evidence. The final clinical practice guidelines and recommendations are presented here, along with the relevant background information.

Comparison of Two Test Strategies for Clarification of Reactive Results for Anti-HBc in Blood Donors

OBJECTIVE

Testing for antibodies against hepatitis B core antigen (anti-HBc) was introduced to detect blood donors suffering from occult hepatitis B infection. Confirmation of specification of reactive results in the anti-HBc screening assay is still a challenge for blood donation services.

METHODS

Two different test strategies for confirmation of specification of reactive anti-HBc tests, one performed in our institute and one suggested by the German authority (Paul-Ehrlich-Institut (PEI)), were compared. The first strategy is based on one supplemental anti-HBc test, the other requires two supplemental anti-HBc tests.

RESULTS

389 samples from 242 donors were considered. Both test strategies yielded concordant results in 117 reactive samples termed 'true-positive' or 'specificity confirmed', in 156 reactive samples termed 'false-positive' or 'specificity not confirmed', and in 99 negative samples. In 17 samples obtained from 11 donors, both test strategies gave discrepant results ('false-positive' but 'specificity confirmed'). In 10 of 11 donors, a real HBV infection was very unlikely, one remained unclear. 30 donors considered 'false-positive' became negative in all anti-HBc tests after follow-up testing and thus eligible for donor re-entry.

CONCLUSIONS

The test strategy suggested by the PEI yielded no additional information but induced an overestimation of HBV infections and unnecessary look-back procedures. Many anti-HBc-reactive donors can be regained after follow-up testing.

High prevalence of occult hepatitis B infection in an African urban population

Occult hepatitis B infection (OBI), the presence of low hepatitis B virus (HBV) deoxyribonucleic acid (DNA) levels in patients without detectable hepatitis B surface antigen (HBsAg), has significant implications for understanding the natural history of hepatitis B infection. We determined the prevalence of OBI in African patients using a sensitive polymerase chain reaction (PCR) assay and describe here the characteristics of OBI in an urban African hospital population. Routine serological testing as well as molecular studies were performed on sera from 314 patients who were part of a previous study from an urban hospital emergency room in Kampala, Uganda, detecting HBV DNA using a nested PCR with amplification of two regions of the HBV genome. HBV viral loads (VL) were determined by real-time PCR (rtPCR) and sequencing performed to determine HBV genotype and S gene mutations. Among 314 subjects tested, 50 (16%) had chronic HBV infection, 94 (30%) had detectable HBV DNA despite testing HBsAg negative (OBI), and 170 (54%) were not infected. VLs of OBI subjects were relatively low although 19 (20%) had VL exceeding 10(4)  IU ml(-) . Subjects with chronic HBV infection had a higher median VL compared to OBI patients (P < 0.001). All chronic HBV sequenced (10) and 83/89 OBI sequences were genotype A, the remaining six being genotype D. S-gene mutations were present in some but not all OBI patients (48%). OBI is more prevalent among African patients than previously thought. This may have implications for clinical management and transfusion-related HBV transmission.