Occult hepatitis B virus infection and blood transfusion

Transfusion-transmitted infections including hepatitis B virus(HBV) have been a major concern in transfusion medicine. Implementation of HBV nucleic acid testing(NAT) has revealed occult HBV infection(OBI) in blood donors. In the mid-1980 s, hepatitis B core antibody(HBc) testing was introduced to screen blood donors in HBV non-endemic countries to prevent transmission of non-A and non-B hepatitis. That test remains in use for preventing of potential transmission of HBV from hepatitis B surface antigen(HBs Ag)-negative blood donors, even though anti-hepatitis C virus testshave been introduced. Studies of anti-HBc-positive donors have revealed an HBV DNA positivity rate of 0%-15%. As of 2012, 30 countries have implemented HBV NAT. The prevalence of OBI in blood donors was estimated to be 8.55 per 1 million donations, according to a 2008 international survey. OBI is transmissible by blood transfusion. The clinical outcome of occult HBV transmission primarily depends on recipient immune status and the number of HBV DNA copies present in the blood products. The presence of donor anti-HBs reduces the risk of HBV infection by approximately five-fold. The risk of HBV transmission may be lower in endemic areas than in non-endemic areas, because most recipients have already been exposed to HBV. Blood safety for HBV, including OBI, has substantially improved, but the possibility for OBI transmission remains.     

Occult hepatitis B virus infection in Egypt

The emerging evidence of the potentially clinical importance of occult hepatitis B virus (HBV) infection (OBI) increases the interest in this topic. OBI may impact in several clinical contexts, which include the possible transmission of the infection, the contribution to liver disease progression, the development of hepatocellular carcinoma, and the risk of reactivation. There are several articles that have published on OBI in Egyptian populations. A review of MEDLINE database was undertaken for relevant articles to clarify the epidemiology of OBI in Egypt. HBV genotype D is the only detectable genotype among Egyptian OBI patients. Higher rates of OBI reported among Egyptian chronic HCV, hemodialysis, children with malignant disorders, and cryptogenic liver disease patients. There is an evidence of OBI reactivation after treatment with chemotherapy. The available data suggested that screening for OBI must be a routine practice in these groups of patients. Further studies needed for better understand of the epidemiology of OBI among Egyptian young generations after the era of hepatitis B vaccination.     

唐山地区献血人群隐匿性乙型肝炎病毒感染分析

目的了解唐山地区无偿献血人群隐匿性乙型肝炎感染情况。方法用ELISA法检测无偿献血者的乙型肝炎血清标志物,对于HBsAg阴性样本,进行HBV核酸检测（NAT）,NAT阳性样本,用罗氏试剂确证HBV DNA载量。结果共检测116 741例血样,证实隐匿性乙型肝炎感染者35例,占总献血人数的0.29‰。其中97.1%隐匿性乙型肝炎感染者样本的HBV DNA滴度低于102IU/ml。在HBV DNA阳性人群中,抗-HBc阳性率较高,占81.5%,抗-HBs阳性或乙型肝炎病毒血清标志物全阴性也可检出HBV DNA分别占55.6%和22.9%。结论唐山地区献血人群中血清HBsAg阴性者存在一定比例的隐匿性HBV感染,其HBV病毒载量均较低,核酸检测能够提高HBV感染的检出率。     

Sensitivity of individual donor nucleic acid testing (NAT) for the detection of hepatitis B infection by studying diluted NAT yield samples

BackgroundScreening blood donors for the presence of hepatitis B virus surface antigen (HBsAg) has been the backbone of blood safety. However, occult hepatitis B infection (OBI) in donors can be missed when only HBsAg screening is used. Nucleic acid testing (NAT) is capable of detecting OBI among donors. The aim of our study was to analyse the sensitivity of NAT for detecting OBI.ResultsOf the 18 samples studied, nine were NAT-reactive at a dilution of <1:4 and five out of these showed presence of antibody to core antigen (IgG+IgM). Antibody to surface antigen was present in only two of the nine NAT-reactive samples, one with antibody to core antigen and the other without. Six had a viral load in the range from <10 to 38 IU/mL whereas the viral load in the remaining three samples was not determined. Among the other nine samples which were NAT-reactive at dilutions ≥1:4, antibody to core antigen (IgG+IgM) was present in seven.DiscussionOur study showed that ID-NAT testing along with HBsAg screening could detect most potentially HBV infectious donors (including those with OBI). NAT screening for HBV on diluted samples could compromise blood safety because samples with a low viral load will escape detection.     

Occult hepatitis B virus infection

Occult hepatitis B virus(HBV)infection(OBI)refers to the presence of HBV DNA in the absence of detectable hepatitis B surface antigen.Since OBI was first described in the late 1970s,there has been increasing interest in this topic.The prevalence of OBI varies according to the different endemicity of HBV infection,cohort characteristics,and sensitivity and specificity of the methods used for detection.Although the exact mechanism of OBI has not been proved,intrahepatic persistence of viral covalently closed circular DNA under the host’s strong immune suppression of HBV replication and gene expression seems to be a cause.OBI has important clinical significance in several conditions.First,OBI can be transmitted through transfusion,organ transplantation including orthotopic liver transplantation,or hemodialysis.Donor screening before blood transfusion,prophylaxis for high-risk organ transplantation recipients,and dialysis-specific infection-control programs should be considered to reduce the risk of transmission.Second,OBI may reactivate and cause acute hepatitis in immunocompromised patients or those receiving chemotherapy.Close HBV DNA monitoring and timely antiviral treatment canprevent HBV reactivation and consequent clinical deterioration.Third,OBI may contribute to the progression of hepatic fibrosis in patients with chronic liver disease including hepatitis C.Finally,OBI seems to be a risk factor for hepatocellular carcinoma by its direct protooncogenic effect and by indirectly causing persistent hepatic inflammation and fibrosis.However,this needs further investigation.We review published reports in the literature to gain an overview of the status of OBI and emphasize the clinical importance of OBI.     

隐匿性乙型肝炎病毒感染的研究进展

隐匿性乙型肝炎病毒感染(occult HBV infection, OBI)是公共健康的一大难题,也是全球临床医学面临的挑战。由于目前检测方法以及临床实际问题的限制,不同研究中对于OBI的定义也不同。OBI的存在会影响临床诊断和输血安全,且OBI在临床高危人群中有再激活的风险,可能会导致肝硬化、肝癌和肝衰竭等终末期肝病。本文就近年OBI定义和不同人群流行率、OBI发生机制以及临床意义等研究进展进行综述。     

Incidence of hepatitis B virus infection in young Chinese blood donors born after mandatory implementation of neonatal hepatitis B vaccination nationwide

This study was carried out to determine the incidence of hepatitis B virus (HBV) infection in the young generation born after mandatory implementation of hepatitis B vaccination since 1992. Repeat blood donors born between 1992 and 1997 were enrolled, who gave blood at least twice during the past 3 years. Donors were tested for HBV infection markers of HBsAg, anti‐HBc, anti‐HBs and viral DNA by immunoassays (EIAs) and nucleic acid tests (NAT). A total of 14 937 pre‐donation screening qualified young repeat donors aged 18‐23 years were tested with 9 (0.06%) being HBsAg by EIA and 10 (1:1494) HBV DNA positive by Ultrio NAT (10.4 IU/mL), respectively. HBV DNA was further detected in 1:192 (9/1732) anti‐HBc+ repeat donors with Ultrio Plus NAT (3.4 IU/mL). Most cases were identified as occult HBV infection (OBI). Of 14 937 repeat donors, 20.9% were anti‐HBc+ positive, while approximately 50% of 12 024 repeat donors were anti‐HBs negative or had levels <100 IU/L. HBsAg+ or OBI strains were classified as wild type of genotype B or genotype C. Incident HBV infection in repeat donors was approximately 1:18.5 person‐years (1.1%/year) but significantly less frequent in donors with confirmed HBV vaccination (2.4%‐3.3%) than those unsure of vaccination status (10.5%; P = .0023). Hepatitis B virus vaccination appears largely protective of HBV infection, but incidence of infections increases in young adults with mostly undetectable or low anti‐HBs or occasionally high anti‐HBs. A boost of hepatitis B vaccine for adolescents prior to age 18 years may reduce HBV infection, and implementation of more sensitive NAT in blood donation screening may improve HBV safety in blood transfusion.     

Update on occult hepatitis B virus infection

The event of mutations in the surface antigen gene of hepatitis B virus(HBV) results in undetectable hepatitis B surface antigen with positive/negative anti-hepatitis B core(anti-HBc) antibody status in serum and this phenomenon is named occult hepatitis B infection(OBI). The presence of anti-HBc antibody in serum is an important key for OBI tracking, although about 20% of OBI cases are negative for anti-HBc antibody. The diagnosis of OBI is mainly based on polymerase chain reaction(PCR) and real-time PCR assays. However, real-time PCR is a more reliable method than PCR. OBI is a great issue for the public health problem and a challenge for the clinical entity worldwide. The persistence of OBI may lead to the development of cirrhosis and hepatocellular carcinoma. With regard to OBI complications, the screening of HBV DNA by the highly sensitive molecular means should be implemented for:(1) patients with a previous history of chronic or acute HBV infection;(2) patients co-infected with hepatitis C virus/human immunodeficiency virus;(3) patients undergoing chemotherapy or anti-CD20 therapy;(4) recipients of organ transplant;(5) blood donors;(6) organ transplant donors;(7) thalassemia and hemophilia patients;(8) health care workers;(9) patients with liver related disease(cryptogenic);(10) hemodialysis patients;(11) patients undergoing lamivudine or interferon therapy; and(12) children in time of HBV vaccination especially in highly endemic areas of HBV. Active HBV vaccination should be implemented for the close relatives of patients who are negative for OBI markers. Thus, the goal of this review is to evaluate the rate of OBI with a focus on status of high risk groups in different regions of the world.     

Occult hepatitis B in blood donors in Indonesia: altered antigenicity of the hepatitis B virus surface protein

Background and aims  

Occult hepatitis B virus infection (OBI) poses a challenge to the safety of blood donation. The prevalence of OBI is not well documented in Indonesia, although this information in such an endemic country is needed. This study was aimed to evaluate the prevalence of occult hepatitis B in blood donors from two cities of Indonesia, and to study the genetic variation and its effect on the predicted antigenicity of HBsAg.     

Epidemiology of occult hepatitis B infection among thalassemic, hemophilia, and hemodialysis patients

Context

Hepatitis B virus (HBV) is the most common disease commuted through blood transfusion. Occult hepatitis B infection (OBI) is a form of the disease which does not present Hepatitis B surface antigens (HBsAg) in the serum of patients; however, HBV-DNA is detectable in the serum and hepatocytes of patients. OBI is an important risk factor to induce post transfusion hepatitis (PTH), cirrhosis, hepatocellular carcinoma (HCC) and reactivation of the HBV. Recently, several reports from various regions of the world have been published regarding PTH among blood recipients as well as HCC, and cirrhosis among patients who require permanent blood transfusion, including diseases such as hemophilia, hemodialysis and thalassemia. This form of the hepatitis also creates problems for individuals that are co-infected with other viruses such as HCV and HIV. To determine the prevalence of OBI among hemophilia, hemodialysis and thalassemia patients is important because it is a high risk factor for PTH, HCC and cirrhosis therefore, its detection is a critical strategy for most health care services. This review addresses recent information regarding prevalence of OBI in relation to the mentioned diseases.

Evidence Acquisition

The data presented here was collected by searching the key words in Pubmed and Scopous databases.

Results

Our searching in the published papers revealed that OBI prevalence is frequent in patients receiving frequent blood transfusions.

Conclusions

it seems that one of the main mechanisms for OBI transmission is most likely through infected blood and its component and evaluation of the prevalence of OBI in donors and patients, especially those with hemophilia and thalassemia should be foul considered.     

Occult Hepatitis B Virus Infection in Hemodialysis Patients: A Concept for Consideration

Hemodialysis patients potentially have an increased risk of infection with parenterally transmitted viral agents due to an impaired host immune response and multiple transfusion requirements. Viral hepatitis is considered as a problem for hemodialysis patients because 1.9% of all deaths among this population are related to the consequence of viral hepatitis. Hepatitis B virus (HBV) is one of the most important causes of transmitted infections by the parenteral route in hemodialysis patients. Occult HBV infection is characterized by presence of HBV infection without detectable hepatitis B surface antigen (HBsAg), which harbors potential risk of HBV transmission through hemodialysis. There are conflicting reports on the prevalence of occult HBV infection (OBI) in hemodialysis patients. Considering the importance of occult HBV infection in hemodialysis patients and the growing evidence on this subject, the purpose of this review is to provide comprehensive information on OBI prevalence in hemodialysis patients and highlight the most important points in this issue.     

Overt and occult hepatitis B virus infection among community children in Northwest China

Although a universal newborn hepatitis B (HB) immunization programme has been implemented in China, hepatitis B virus (HBV) breakthrough infection, including HB surface antigen (HBsAg)‐positive infection and occult HBV infection (OBI), still occurs during infancy or childhood. Obtaining the actual prevalence of HBV infection in general children is important for preventing and controlling the spread of HB. Accordingly, we investigated the prevalence of overt infection and OBI in community children and compared the serological and virological characteristics of OBI and HBsAg carrier children to clarify the mechanisms related to OBI. In total, 6 706 community children <12 years of age were included from a population‐based HBV seroepidemiological investigation in Northwest China. The HBsAg carrier rate in community children was 1.60% (107/6706), and the anti‐HBs positive rate was 57.35% (3846/6706). Additionally, 1192 HBsAg‐negative children were examined for OBI using nested PCR. The prevalence of OBI in local children was 1.26% (15/1192), and the predominant OBI genotypes were C and D. The 15 OBI children and 29 HBsAg‐positive children from the same population did not have a statistical significant difference in age, gender, alanine aminotransferase (ALT), proportion of anti‐HBs or anti‐HBc, viral genotypes or mutations. Children with chronic overt infection had higher viral loads than OBI children (P=.004). These results suggested that HBV overt and occult infection of children was more serious in underdeveloped north‐west regions. HBV neonatal immunization and catch‐up programmes should be strengthened and supplemented. None of specific viral mutations or genotypes related to OBI were found. OBI may be a specific stage of HBV infection.     

Lack of occult hepatitis B virus infection among blood donors with isolated hepatitis B core antibody living in an HBV low prevalence region of Iran

BackgroundOccult hepatitis B virus (HBV) infection in blood donors is considered a potential threat for the safety of the blood supply, however conclusive studies on this issue are lacking. The aim of this study was to assess the occult HBV infection in blood donors with isolated hepatitis B core antibody (anti-HBc) living in the city of Arak, in the Central Province of Iran, as a low prevalence region for HBV.MethodsA total of 531 voluntary blood donors in Arak, Iran were included in this study. Hepatitis B surface antigen (HBsAg), hepatitis B surface antibody (anti-HBs), anti-HBc, and hepatitis C antibody (anti-HCV) were tested in all subjects. The presence of HBV-DNA was determined quantitatively in plasma samples of cases with isolated anti-HBc (HBsAg-negative, anti-HBs-negative, and anti-HBc-positive) by real-time PCR using the artus HBV RG PCR kit on the Rotor-Gene 3000 real-time thermal cycler.ResultsOf 531 subjects enrolled in this study, 11 (2.1%, 95% confidence interval 0.8–3.2%) had isolated anti-HBc. HBV-DNA was not detected in any of the cases with isolated anti-HBc.ConclusionsOur study showed that all the blood donors with isolated anti-HBc were negative for HBV-DNA, and occult HBV infection did not occur in the blood donors of this low prevalence region for HBV infection.     

Clinical significance of occult hepatitis B virus infection: illustrative cases

Occult HBV infection (OBI) is an increasingly reported form of hepatitis B virus (HBV) infection, With the current knowledge, in immunocompetent individuals, OBI is mainly a diagnostic challenge and has a very low probability of transfusion risk, controversial risk of liver disease or hepatocellular carcinoma, etc. In immunosuppressed individuals, however, reactivation of OBI is a real concern even today. There are many controversies about the management of such cases, including anti-HBc and/or alanine aminotransferase monitoring, HBV DNA monitoring, vaccination or pre-emptive nucleoside analogs. We present here four OBI cases which reveal the difficulties in the diagnosis and management of OBI and include a discussion upon current literature.     

Prevalence and clinical significance of occult hepatitis B virus infection among renal transplant recipients in Korea

Abstract Background: Occult hepatitis B infection (OBI) is the presence of hepatitis B virus (HBV) DNA in serum or hepatic tissue without detectable hepatitis B surface antigen (HBsAg) in serum. Kidney disease patients in the post-renal transplantation period are in a specific situation as a result of the high pre-transplantational risk of HBV infection and post-transplantational immunosuppression. We studied the pre-transplantational prevalence and post-transplantational influence of OBI on kidney transplantation patients. Methods: We investigated pre-transplantational serum samples of 217 HBsAg-negative patients of post-renal transplant status for the presence of HBV DNA by real-time quantitative polymerase chain reaction. Serologic markers for HBV and hepatitis C virus (HCV) infection as well as liver enzymes were analyzed. Results: We detected HBV DNA in 2.3% (5/217) of HBsAg-negative patients, and the median HBV DNA titer was 33.15 copies/ml (range 30.6-144.6 copies/ml). Among the 5 OBI patients, 2 had hepatitis B surface antibodies (anti-HBs) and 1 had hepatitis B core antibodies (anti-HBc IgG). None of the patients with OBI were co-infected with HCV. There was no evidence of reactivation of OBI during the 36-month (range 27-63 months) follow-up monitoring period after transplantation, in spite of immune suppression to prevent rejection. Conclusions: The prevalence of occult HBV in the setting of renal transplantation was higher than that in the general population of Korea, and no reactivation of hepatitis B was observed in patients with OBI in the post-renal transplantation period.     

Occult Hepatitis B: Clinical Implications and Treatment Decisions

First reported in 1978, occult hepatitis B is a term used to describe the presence of hepatitis B virus (HBV) DNA without hepatitis B surface antigenemia. The prevalence of occult HBV is unclear and depends in part on the sensitivity of the hepatitis B surface antigen (HBsAg) and DNA assays used as well as the prevalence of HBV infection in the study population. The origin of occult HBV also remains in question. Several mechanisms have been hypothesized including mutations in the regulatory regions of the HBV genome, persistence of Ig-bound HBV immune complexes, viral interference, and blockage of free HBsAg secretion. Occult HBV has important clinical implications such as transmission through blood transfusion, reactivation in the setting of immunosuppression, and interference with hepatitis C treatment. To date, there is little data pertaining to the treatment of occult HBV outside of the setting of chemotherapy-induced HBV reactivation.     

Diagnostic strategy for occult hepatitis B virus infection

In 2008,the European Association for the study of the liver(EASL) defined occult hepatitis B virus infection (OBI) as thepresence of hepatitis B virus(HBV) DNA in the liver(with detectable or undetectable HBV DNA in the serum) of individuals testing hepatitis B surface antigen(HBsAg) negative by currently available assays.Several aspects of occult HBV infection are still poorly understood,including the definition itself and a standardized approach for laboratory-based detection,which is the purpose of this ...     

Occult hepatitis B virus infection: implications in transfusion

Hepatitis B virus (HBV) presents a higher residual risk of transmission by transfusion than hepatitis C virus (HCV) or human immunodeficiency virus (HIV). While most infectious blood units are removed by screening for hepatitis B surface antigen (HBsAg), there is clear evidence that transmission by HBsAg-negative components occurs, in part, during the serologically negative window period, but more so during the late stages of infection. Donations negative for HBsAg, but positive for HBV DNA, with or without the presence of HBV antibodies, correspond to 'occult' HBV infection (OBI). The frequency of OBI depends on the relative sensitivity of both HBsAg and HBV DNA assays. It also depends on the prevalence of HBV infection in the population. OBI may follow recovery from infection, displaying antibody to hepatitis B surface antigen (anti-HBs) and persistent low-level viraemia, escape mutants undetected by the HBsAg assays, or healthy carriage with antibodies to hepatitis B e antigen (anti-HBe) and to hepatitis B core antigen (anti-HBc). Over time, in the latter situation, anti-HBe and, later, anti-HBc may become undetectable. The critical question is whether or not OBI is infectious by transfusion. All forms have been shown to be infectious in immunocompromised individuals, such as organ- or bone marrow-transplant recipients. In immunocompetent recipients, there is no evidence that anti-HBs-containing components (even at low titre) are infectious. Anti-HBc only, with HBV DNA, can be associated with infectivity, as can rare cases of HBV DNA without any serological HBV marker. If HBV nucleic acid amplification technology (NAT) is considered, the OBI viral load would usually be < 500 IU/ml, making testing of plasma pools unsuitable unless the sensitivity of NAT significantly increases by genome enrichment or test improvement.     

Occult Hepatitis B Virus (HBV) Infections: Hepatitis B Surface Antigen (HBsAg) Negative and Primary Occult

Occult HBV infection (OBI) is defined as persistence of HBV genomes (with detectable or undetectable serum HBV DNA) in the liver of serum HBsAg negative individuals. It represents the HBsAg negative phase of the natural history of HBV infection in individuals with self-limited acute hepatitis B or in HBsAg carriers or chronic hepatitis B patients who lose HBsAg either naturally or after antiviral therapy and maintain lifelong anti-HBc in serum (with or without anti-HBs and\or anti-HBe). Rarely it may occur as primary “occult” infection when caused by minute viral amounts unable to induce humoral immune response. HBsAg negative infections stem from lifelong intrahepatic persistence of HBV-ccc-DNA under the host’s immune control and may lead to HBsAg positive reactivation after immunosuppressive therapies or epigenetic modifications. HBV reactivation can be avoided by pre-emptive antiviral therapy with nucleos(t)ide analogs. OBI in chronic liver disease of other etiologies may contribute to the development of hepatocellular-carcinoma.     

Prophylaxis of hepatitis B reactivation with immunosuppressive therapy in rheumatic diseases. Orientations for clinical practice

Reactivation of infection with hepatitis B virus (HBV) is a potentially serious complication of immunosuppression, which can be identified and efficiently prevented. There have been an increasing number of cases of HBV reactivation in patients receiving immunosuppression in the context of rheumatic diseases such as rheumatoid arthritis or systemic lupus erythematosus. The recommendations in this area should be individualized taking into account two aspects: immunosuppressive regimens used (high or low risk of reactivation) and the different stages of HBV infection: chronic hepatitis B, inactive HBV carrier, occult hepatitis B infection defined by HB surface antigen (HBsAg) negative and antibody anti-HB core (anti-HBc) positive. In patients with rheumatic diseases that will start high-risk immunosuppressive drugs, we propose a universal screening with serological tests for hepatitis B (HBsAg, anti-HBs and anti-HBc). Patients with chronic hepatitis B (HBsAg positive, HBV DNA ≥ 2000 IU/ml, elevated ALT) should initiate antiviral therapy. Inactive HBV carriers (HBsAg positive, HBV DNA <2000 IU / ml, normal aminotransferases) exposed to high risk immunosuppressive therapy should undergo prophylaxis of HBV reactivation. Prophylaxis should be started 2 to 4 weeks before the beginning of immunosuppressive therapy and maintained for at least 6 to 12 months after its suspension. It is recommended to use entecavir or tenofovir as first line antiviral agents. In inactive HBsAg carriers under low-risk immunosuppressive therapy and patients with HBsAg negative/anti-HBc positive (HBV infection in the past), the strategy should be monitoring of viral reactivation with aminotransferases and HBV DNA determination in every 6 months.