Prevalence of parenterally transmitted hepatitis viruses in clinically diagnosed cases of hepatitis

Hepatitis B virus (HBV) is the most important causative agent of blood borne hepatitis in humans. Hepatitis D Virus (HDV) infection occurs either as a coinfection or superinfection in HBV carriers. Hepatitis C virus (HCV) is the major cause of transfusion non-A, non-B hepatitis and continues to be a major cause of human liver disease throughout the world. The present study was conducted on 70 clinically diagnosed cases of viral hepatitis to study the prevalence of parenterally transmitted viral hepatitis. The serum samples were tested for HBsAg, HBeAg, IgM anti-HBc, anti-HBe, anti-HCV and anti-HDV using separate ELISA kits. Of the 70 serum samples tested, 28 (40%) were positive for HBsAg out of which 3 (4.28%) were positive for HBeAg also. Five (7.1%) of the HBsAg positive cases tested positive for IgM anti-HBc also. HBsAg alone was found in 17 (24.28%) cases. The prevalence of anti-HCV was 3 (4.28%) in 70 cases. Thus early screening of clinically diagnosed cases of viral hepatitis is essential for establishing diagnosis and treatment to prevent long term sequelae.     

Acute and chronic hepatitis delta virus infection: Direct or indirect effect on hepatitis B virus replication?

In a large population of patients, chronic hepatitis delta virus (HDV) infection was usually associated with absence of hepatitis B virus (HBV) replication. However, acute HDV superinfection progressing to chronic HDV infection in two hepatitis B e antigen (HBeAg)-positive HBV carriers and coinfection in two other patients who progressed to chronic HBV (HBeAg-positive) and HDV infection was associated with continuing high-level HBV replication for several years. Thus HDV infection does not always inhibit HBV replication. The hypothesis that the different effects of HDV coinfection and superinfection on HBV replication may stem from variability in the capacity of the host to produce and respond to interferon is discussed.     

Molecular epidemiology of hepatitis delta virus (HDV) in Iran: A preliminary report

To identify hepatitis delta virus (HDV) genetic variability and its circulating genotypes amongst infected Iranian patients, 25 patients with positive anti‐HDV status from different parts of Iran were enrolled in this cross‐sectional study. A portion of the HDV delta antigen was amplified, sequenced, and subjected to molecular and phylogenetic analysis. Clinical features and virological markers were evaluated. HDV RNA could be detected in 88% of anti‐HDV positive cases (22 patients) with chronic hepatitis B virus (HBV) infection and liver cirrhosis. Phylogenetic analysis revealed that all Iranian patients were infected by genotype I (clade 1) of HDV, supported by a high bootstrap value (100%, 1,000 replicates). All HDV‐positive patients were coinfected with genotype D1 of HBV. No significant association was determined between demographic, clinical, and virological variables in the population studied. In conclusion, the present molecular epidemiology survey reveals that clade 1 of HDV is predominant among coinfected HBV patients in Iran. J. Med. Virol. 80:2092–2099, 2008. © 2008 Wiley‐Liss, Inc.     

Concurrent hepatitis C virus and hepatitis delta virus superinfection in patients with chronic hepatitis B virus infection.

Since hepatitis C virus (HCV) and hepatitis delta virus (HDV) are transmitted by the same routes as hepatitis B virus (HBV), simultaneous or concurrent HCV and HDV infection in patients with chronic HBV infection may occur. To test this hypothesis and to examine the clinicohistological and immunopathological presentations of such multiple hepatitis virus infections, acute and/or convalescent serum specimens from 86 patients with acute HDV superinfection were tested by enzyme immunoassay for antibodies to HCV. Of the 86 patients, 18 (20.9%) were associated with HCV infection. Although patients with early mortality cannot be evaluated by the HCV markers used in this study, the results showed that the clinical and histologic features were similar except that patients with HCV infection were older than those without HCV infection (P less than 0.01). Immunopathological studies carried out within 2 months after the onset of acute HDV superinfection demonstrated that hepatitis B core antigen (HBcAg) was not detected in any patient and HDV antigen was detected in 18.2% of the patients with HCV infection whereas HBcAg and HDAg were found in 7% and 65.1%, respectively, of those without HCV coinfection (P less than 0.02). It is concluded that concurrent HCV and HDV superinfections can and do occur in patients with chronic HBV infection. In these triple viral infections, HCV may even transiently suppress HDV and HBV.     

High prevalence of hepatitis B,C and delta virus infections among blood donors in Mongolia

Summary. Serum samples obtained from 289 first-time and 114 repeat donors at the Blood Center of Mongolia (MBC) were tested for serological and molecular markers of hepatitis B virus (HBV), hepatitis C virus (HCV), and hepatitis delta virus (HDV) infections. Among the 403 blood donors, 33 (8.2%), 21 (5.2%), and 27 (6.7%) tested positive for hepatitis B surface antigen (HBsAg) and/or HBV DNA, HCV RNA, and HDV RNA, respectively. Collectively, 55 donors were viremic for one or more of these viruses, and included 54 first-time donors (18.7%) and 1 repeat donor (0.9%) (P < 0.0001). One discrepant case with HBsAg detectable only at MBC was negative for HBsAg, HBV DNA and anti-HBc in this study. Four donors who were HCV-viremic in this study were negative for anti-HCV by the MBC method. Further efforts to increase the sensitivity and specificity of the currently-used tests are urgently required in Mongolia. Three donors who were positive for anti-HBc and anti-HDV but negative for HBsAg, had both HBV DNA and HDV RNA. This suggests that introduction of a new anti-HDV serological test is useful for not only HDV screening but also HBV screening of anti-HBc-positive, HBsAg negative donors, considering a possibility of viral interference by coexisting HDV.     

Prevalence, risk factors, and molecular epidemiology of hepatitis B and hepatitis delta virus in pregnant women and in patients in Mauritania

No recent data are available on hepatitis B virus (HBV) and hepatitis Delta virus (HDV) prevalence in Mauritania. One thousand twenty pregnant women and 946 patients visiting for routine checkups were screened for HBV and HDV infection. Demographic, epidemiological, ethnic, clinical, and biological data were recorded. HBV and HDV genotypes were determined by sequencing and phylogenetic analyses. In the pregnant women and patients cohorts, respectively, the prevalence of HBsAg (10.7% and 18.3%) and anti‐HBcAb (66.3% and 76.5%) indicated high HBV endemicity. In pregnant women, exposure to HBV was significantly associated in multivariate analysis with education level, ethnicity, blood transfusion, and occupation. HDV antibodies (HDVAb) were found in 14.7% of pregnant women. In patients, HBsAg was found less frequently in females than in males. Again in multivariate analysis, exposure to HBV was significantly correlated with gender (males), and HDVAb positivity with age and gender. The HBV DNA viral load was >3 log IU/ml in only 10.1% of pregnant women and in 17.3% of patients. HDV‐RNA was detectable in 21 (67.7%) of the 31 patients positive for HDVAb, and in 11 of the 16 pregnant women positive for HDVAb (68.8%). The most frequent HBV genotypes were: HBV/D, 53%; HBV/E, 35%; and HBV/A, 12%. Sub‐genotyping revealed HBV/D1,/D7, and the recently described/D8. HDV genotypes were: HDV‐1, 90.3% and HDV‐5, 9.7%. This study confirms the high prevalence of HBV and HDV infections in Mauritania and demonstrates the high genetic diversity of HBV in this country. J. Med. Virol. 84: 1186–1198, 2012. © 2012 Wiley Periodicals, Inc.     

Prevalence and clinical significance of hepatitis D virus co-infection in patients with chronic hepatitis B in Korea

Hepatitis D virus (HDV) infection can cause severe acute and chronic liver disease in patients infected with hepatitis B virus (HBV). Despite the significant decline in the global HDV infection, it remains a major health concern in some countries. This study aimed to investigate the prevalence and clinical features of HDV co-infection in patients with chronic HBV infection in Korea, where HBV infection is endemic. Nine hundred forty patients [median age, 48 (18-94) years; men, 64.5%] infected chronically with HBV were enrolled consecutively. All patients who were positive for hepatitis B surface antigen (HBsAg) for at least 6 months and were tested for anti-HDV. A portion of the HDV delta antigen was amplified, sequenced, and subjected to molecular and phylogenetic analysis using sera from the patients who were anti-HDV positive. Clinical features and virologic markers were evaluated. Inactive HBsAg carriers, chronic hepatitis B, cirrhosis and hepatocellular carcinoma accounted for 29.5%, 44.7%, 17.9%, and 8.0%, respectively. Only three patients were positive for anti-HDV, corresponding to a 0.32% positive rate. All patients who were positive for anti-HDV were inactive HBsAg carriers. HDV RNA could be amplified by PCR from the sera of two patients. Phylogenetic analysis showed that both carried HDV genotype 1. In conclusion, the prevalence of HDV infection is very low (0.32%) in Korea. All HDVs were genotype 1 and detected in inactive HBsAg carriers. Therefore, HDV co-infection may not have a significant clinical impact in Korean patients with chronic HBV infection.     

Kinetics of HBV DNA and HBsAg in acute hepatitis B patients with and without coinfection by other hepatitis viruses

The kinetics of hepatitis B virus (HBV) and its surface antigen (HBsAg) during acute hepatitis has not yet been studied accurately in a representative number of patients. The influence of coinfecting hepatitis viruses during the acute phase of infection is not known. Three to four serum samples from 21 patients with acute HBV monoinfection and 27 with coinfection were taken at intervals of 6-10 days and analyzed for the number of HBV genome equivalents (ge) by real time polymerase chain reaction (PCR) and for HBsAg quantity using Laurell electrophoresis. Log HBV ge/ml decreased during the follow-up from 6.8 +/- 1.1 to 5.1 +/- 1.0 to 4.2 +/- 0.8 to 3.3 +/- 1.1 (mean +/- SD). The half-life times of HBV ge increased from 1.6 days at the beginning to 4 days at the end. HBsAg decreased much slower: from 38 to 23 to 12 to 3.8 microg/ml. Half-life time was around 8 days at the beginning and 5.7 days at the end, but 11 patients showed a rapid elimination of HBsAg and HBV DNA. Hepatitis C virus (HCV) coinfection did not change the kinetics of HBV ge and HBsAg significantly. A moderate but significant suppression of HBV ge levels was observed in hepatitis D virus (HDV) coinfected patients. HBsAg levels were, however, enhanced in this cohort. In conclusion, the data suggest that expression and elimination of HBV is in most patients with acute hepatitis B not altered by coinfecting hepatitis viruses. The initial decrease of HBV ge and HBsAg in serum appears to be caused by decay or non-specific removal in the absence of replacement.     

Molecular characterization of occult hepatitis B cases in Greek blood donors

The use of sensitive nucleic acid testing for hepatitis B virus in blood donors revealed a number of HBV DNA(+) cases among HBsAg(?) donors, a status known as occult HBV infection. The purpose of this study was the serological and molecular characterization of occult HBV infection in Greek blood donors. A prospective study was undertaken in order to identify occult HBV infection cases in blood donors. As part of the routine screening of blood donations in Greece, blood units were screened individually by a multiplex HIV‐1/HCV/HBV nucleic acid assay. Initially reactive samples were retested with discriminatory assays. HBV DNA(+)/HBsAg(?) samples were tested further for HBV serological markers and HBV DNA was quantified by real‐time PCR. Molecular characterization was performed by sequencing the envelope and polymerase genes of HBV. Preliminary screening revealed 21 occult cases with the following patterns: anti‐HBc only: 7 donors, anti‐HBc/anti‐HBs: 7 donors, anti‐HBc/anti‐HBe: 5 donors, anti‐HBc/anti‐HBs/anti‐HBe: 2 donors. In all cases, the HBV DNA load was <351 IU/ml. Sequencing was successful in 10 donors (classified within genotype D) revealing several amino acid substitutions related to diagnostic escape and antiviral resistance. HBsAg diagnostic failure and low viral replication in occult HBV infection carriers could possibly be attributed to multiple changes in envelope and polymerase regions, respectively. J. Med. Virol. 81:815–825, 2009. © 2009 Wiley‐Liss, Inc.     

Hepatitis B virus concentrations in serum determined by sensitive quantitative assays in patients with established chronic hepatitis delta virus infection.

To clarify the correlation between hepatitis B virus (HBV) DNA levels and serum alanine aminotransferase (ALT) levels in patients with established chronic hepatitis delta virus (HDV) infection, sensitive HBV quantitative assays were used for the study. Thirty-four consecutive patients with chronic liver disease who were positive for both hepatitis B surface antigen (HBsAg) and antibody to HDV (anti-HDV), including 19 patients with chronic hepatitis, 8 patients with liver cirrhosis and 7 patients with hepatocellular carcinoma. All were negative for hepatitis Be antigen (HBeAg) and positive for antibody to HBeAg. HBV DNA was detected in 25 (73.5%) of the 34 patients using real-time detection PCR, and the HBV DNA levels of these patients were significantly lower compared with HBeAg status and ALT level-matched patients with chronic liver disease positive for HBsAg but negative for anti-HDV. There was no correlation between serum HBV DNA and ALT levels among the 34 patients with chronic liver disease positive for anti-HDV. Whereas serum ALT levels in anti-HDV-positive HBsAg carriers with HDV RNA were significantly higher than those without HDV RNA. Liver damage in patients with established chronic HDV infection may be caused mainly by ongoing HDV infection not by HBV replication.     

Influence of hepatitis delta virus superinfection on the clearance of hepatitis B virus (HBV) markers in HBV carriers in Japan

To elucidate the influence of hepatitis delta virus (HDV) superinfection on the clearance of hepatitis B virus (HBV) associated antigens in HBV carriers, we examined for antibody to hepatitis delta antigen (anti-HD) serial sera collected from 1,029 HBV carriers in Kure, Japan. Of the 242 HBV carriers with hepatitis B e antigen (HBeAg), 28 became seropositive for anti-HD, of whom 18 (64.3%) cleared HBeAg; 214 did not become seropositive for anti-HD, of whom 70 (32.7%) cleared HBeAg. Thus, HBeAg clearance was observed in a significantly higher proportion of HDV-superinfected carriers as compared with carriers without HDV infection (P less than 0.005). In the 56 HBV carriers who cleared hepatitis B surface antigen (HBsAg), anti-HD was detected in three cases with increased serum alanine aminotransferase activity preceding HBsAg clearance. The duration of anti-HD seropositive state was less than 5 years, and the titer of anti-HD was relatively low in every case. These data suggest that the HDV infection rate in Japan is higher than previously reported, that HDV superinfection can be one of the factors that induce the HBeAg clearance and HBsAg clearance in HBV carriers, and also that the most likely outcome of HDV superinfection in HBV carriers in Japan may be acute self-limited infection.     

Development of a hepatitis delta virus antibody assay for study of the prevalence of HDV among individuals infected with hepatitis B virus in China

Co-infection with hepatitis delta virus (HDV) and hepatitis B virus (HBV) has been shown to be associated with a more severe form of acute and chronic hepatitis. Cloning and expression of recombinant HDV antigen (rHDAg) in Escherichiacoli are described. Using purified rHDAg, a cost-effective indirect anti-HDV enzyme-linked immunosorbent assay (ELISA) kit was developed. Direct comparison of 15 known HDV-positive sera and 15 HDV-negative sera showed concordance agreement between the new assay kit and the Abbott Murex Anti-Delta (total) kit. In addition, 1,486 hepatitis B surface antigen (HBsAg) positive blood samples collected from various areas of China were tested using this indirect anti-HDV ELISA. It was found that 1.2% (95% CI: 0.7-1.9%) of the samples were anti-HDAg positive. It is suggested that the prevalence of HDV and HBV co-infection in China is relatively low.     

Prevalence of hepatitis D virus infection in hepatitis B surface antigen-positive subjects in Golestan province, northeast Iran

BACKGROUND AND PURPOSE: Hepatitis D virus (HDV) is a defective RNA virus dependent on hepatitis B virus (HBV) infection for its replication and expression. It is known that coexistent infection with HDV tends to aggravate the course of HBV-associated liver disease. This study was carried out to determine the seroprevalence of HDV among hepatitis B surface antigen (HBsAg)-positive individuals in the northeast part of Iran. METHODS: 139 HBsAg-positive subjects detected from a population-based single stage cluster sampling in Golestan province of Iran were enrolled. All cases were evaluated for the presence of anti-HDV antibodies using commercially available enzyme-linked immunoabsorbent assay kits. Logistic regression was used to determine the relationship between independent variables and HDV seropositivity. RESULTS: Of 139 cases, 68 were males (48.9%) and 71 were females (51.1%). The mean age was 41.9 +/- 11.3 years (range, 25-64 years). Anti-HDV antibody was positive in 8 subjects (5.8%), with a female predominance (9.9% vs 1.5%, p=0.06; odds ratio, 7.32; 95% confidence interval, 0.87-61.23). No significant relationship was seen between anti-HDV seropositivity and demographic factors such as age, place of residence and marital status. CONCLUSIONS: These findings show that HDV infection is endemic in Golestan province (northeast) of Iran. Seroprevalence of anti-HDV in the present study was higher than in some previous studies from other parts of Iran. Our results suggest that the prevalence of HBV/HDV coinfection in Golestan province of Iran has increased during the last decade. Therefore, practitioners and health care managers should be made aware of the risk of dual infection with HBV and HDV.     

衢州市无偿献血者中隐匿性HBV感染的基因型别及突变类型分析

目的 了解衢州市无偿献血者隐匿性乙肝病毒感染情况及病毒的分子生物学特征.方法 对衢州市中心血站24 178例无偿献血者血液用北京万泰和Sorin公司生产的ELlSA试剂盒进行HBV的初检和复检,对HBsAg阴性标本进行HBV DNA检测,从而检出隐匿性乙肝病毒感染者,再对HBV DNA 阳性标本进行 S 基因片段序列分析和氨基酸突变分析,从而了解本市无偿献血者隐匿性乙肝病毒感染情况和病毒分子生物学特征,探讨隐匿性乙肝病毒感染的可能机制.结果 24 178例无偿献血者标本中,158例HBsAg阳性,24 020例HBsAg阴性标本中,15例HBV DNA阳性,隐匿性HBV感染比例为0.62‰（15/24 020）,其中基因C型9例（60％）,基因B型6例（40％）;S基因“a”表位氨基酸突变分析显示有11例隐匿性HBV感染病毒株在“a”表位发生突变.结论 衢州市无偿献血者中存在一定比例隐匿性乙肝病毒感染,隐匿性乙肝病毒感染与病毒基因突变有相关性.     

Fulminant hepatitis in asymptomatic hepatitis B surface antigen carriers in Greece

Eleven male fulminant hepatitis (FH) patients (mean age: 47.7 +/- 16 years) positive for hepatitis B surface antigen (HBsAg) but negative for IgM antibody to hepatitis B core antigen (IgM anti-HBc) were admitted consecutively to the Athens Hospital for Infectious Diseases between May 1981 and November 1983. Because of the absence of IgM anti-HBc, determined by an enzyme immunoassay, these patients were considered to be HBsAg carriers with a superimposed acute hepatitis. Three of the 11 patients received immunosuppressive chemotherapy during the six months before the onset of the acute hepatitis. None of the patients was homosexual or a drug addict. Infection with hepatitis A virus (HAV), hepatitis B virus (HBV), or hepatitis delta virus (HDV) was detected with serologic markers and/or molecular hybridization techniques. Fulminant hepatitis was attributed to spontaneous reactivation of chronic hepatitis B in four patients, chemotherapy-induced reactivation of chronic hepatitis B in three patients, HDV superinfection in one patient and possible superinfection by non-A, non-B agent(s), HDV, or HDV-like agents in three patients. Reactivation of chronic hepatitis B was an important cause of apparent acute hepatitis in heterosexual male HBsAg carriers from an area with a high prevalence of HBV infection.     

Infection with hepatitis A, B, C, and delta viruses among patients with acute hepatitis in Mongolia

One hundred ten consecutive patients (60 males and 50 females; age, mean +/- standard deviation [SD], 22.6 +/- 6.4 years; range 16-48 years) who were clinically diagnosed with sporadic acute hepatitis between December 2004 and January 2005 in Ulaanbaatar, Mongolia, were studied. IgM antibodies to hepatitis A virus were detected in 18 patients (16.4%), IgM antibodies to hepatitis B core (anti-HBc IgM) in 38 patients (34.5%) including two patients with concurrent hepatitis delta virus (HDV) infection, and hepatitis C virus RNA in nine patients (8.2%). There were 30 hepatitis B virus (HBV) carriers who had detectable hepatitis B surface antigen and antibodies to HDV but were negative for anti-HBc IgM, suggesting that they acquired type D acute hepatitis due to superinfection of HDV on a background of chronic HBV infection. None had IgM antibodies to hepatitis E virus (HEV). Consequently, 16.4, 32.7, 6.4, 1.8, and 27.3% of the patients were diagnosed as having acute hepatitis of type A, B, C, type B + D (HBV/HDV coinfection), and type D (superinfection of HDV), respectively. The cause of hepatitis was not known in the remaining 17 patients (15.5%). All 18 HAV isolates were genotyped as IA, all 9 HCV isolates were genotyped as 1b, and all 32 HDV isolates were classified into genotype I. The distribution of HBV genotypes among the 67 HBV isolates was A (1.5%, n = 1) and D (98.5%, n = 66). The present study indicates that de novo infections of HAV, HBV, HCV, and HDV are prevalent among young adults in Mongolia.     

成年树鼩实验感染丁型肝炎病毒的初步研究

在证实成年树可感染人乙型肝炎病毒（ＨＢＶ）的基础上，进行了丁型肝炎病毒－乙型肝炎病毒（ＨＤＶ／ＨＢＶ）实验感染的探索。ＨＤＶ／ＨＢＶ阳性人血清经同时和重叠感染方式接种于成年树后，定期留取感染树血清及肝组织，检测血清中ＨＢｓＡｇ、ＨＤＡｇ、抗－ＨＤ、ＨＢＶＤＮＡ及ＨＤＶＲＮＡ，初步探讨成年树实验感染ＨＤＶ的可能性。研究发现：①成年树对人ＨＢＶ易感，ＨＢｓＡｇ阳性率为７５％，其血清学反应及肝组织病理改变与文献报道一致；②ＨＤＶ可通过同时和重叠两种方式感染成年树，感染树血清中可出现ＨＤＡｇ及抗－ＨＤ，经分子杂交证实其血清及肝内均有ＨＤＶＲＮＡ和ＨＢＶＤＮＡ存在，且可导致明显的肝细胞损伤。结果提示：成年树既可感染人ＨＢＶ也可感染ＨＤＶ，可作为研究ＨＤＶ人工感染的实验动物；成年树感染ＨＤＶ后的特点与人及黑猩猩感染时十分相似，能较好地反映人丁型肝炎的真实情况。     

Isolated serum hepatitis B core antibody seropositivity: A diagnostic risk factor for occult hepatitis B infection

Anti‐HBc screening and nucleic acid testing for hepatitis B viral DNA (HBV DNA) detection in blood donors are not routinely performed in clinical settings in Nigeria. This raises serious concerns for safety of blood at a time that global health standards advocate for transfusion safety. The aim of this research is to investigate if presence of anti‐HBc in blood donors is actually associated with occult hepatitis B infection through basic and advanced procedures. Prospective blood donors who were seronegative for HBsAg but sero‐positive for anti‐HBc (with or without other markers) among the four hundred and seventy enrolled in a cross‐sectional study were selected for this study. Samples were further screened for hepatitis B core immunoglobulin M by enzyme‐linked immunosorbent assay. Nucleic acid testing was performed for confirmation of occult hepatitis B infection. Anti‐HBc was detected in 20 (32.8%) of the sixty‐one HBsAg antigen‐negative blood donors which constituted 13.0% of the total number of enrolled blood donors. Anti‐HBc total‐positive differentiation showed eighteen (90.0%) anti‐HBc (IgG) and two (10%) anti‐HBc (IgM) were detected. Nucleic acid testing showed 5.0% prevalence of occult hepatitis B infection among the anti‐HBc‐positive blood donors with estimated HBV DNA viral load of 58 IU/ml. Demonstration of 5.0% occult hepatitis B prevalence showed the possibility of post‐transfusion hepatitis B infection in transfusion recipients with consequent possible liver damage should hepatitis B surface antigen alone be the continued practice in clinical settings. The inclusion of antibody to hepatitis B core antigen screening in addition to hepatitis B surface antigen marker is an essential step to ensuring optimal blood safety and prevent post‐transfusion hepatitis.     

Occult hepatitis B virus (HBV) infection in healthy blood donors

Blood transfusion is an important route of transmission of hepatitis B virus (HBV). Occult HBV infection can exist in the absence of HBsAg and can be detected by determining HBV DNA. To determine the occult HBV infection in healthy blood donors. One hundred adult healthy blood donors, negative for HBsAg, anti HCV, HIV-1 and other risk factors were screened for HBV DNA by PCR. All the healthy blood donors were negative for HBV DNA by PCR. Occult HBV infection does not occur in the healthy blood donors in the population studied.