Transmission of Hepatitis C Virus From Organ Donors Despite Nucleic Acid Test Screening.

Nucleic acid testing (NAT) for hepatitis C virus (HCV) is recommended for screening of organ donors, yet not all donor infections may be detected. We describe three US clusters of HCV transmission from donors at increased risk for HCV infection. Donor's and recipients' medical records were reviewed. Newly infected recipients were interviewed. Donor-derived HCV infection was considered when infection was newly detected after transplantation in recipients of organs from increased risk donors. Stored donor sera and tissue samples were tested for HCV RNA with high-sensitivity quantitative PCR. Posttransplant and pretransplant recipient sera were tested for HCV RNA. Quasispecies analysis of hypervariable region-1 was used to establish genetic relatedness of recipient HCV variants. Each donor had evidence of injection drug use preceding death. Of 12 recipients, 8 were HCV-infected-6 were newly diagnosed posttransplant. HCV RNA was retrospectively detected in stored samples from donor immunologic tissue collected at organ procurement. Phylogenetic analysis showed two clusters of closely related HCV variants from recipients. These investigations identified the first known HCV transmissions from increased risk organ donors with negative NAT screening, indicating very recent donor infection. Recipient informed consent and posttransplant screening for blood-borne pathogens are essential when considering increased risk donors.

Drug resistance of a viral population and its individual intrahost variants during the first 48 hours of therapy.

Using hepatitis C virus (HCV) and interferon (IFN) resistance as a proof of concept, we have devised a new method for calculating the effect of a drug on a viral population, as well as the resistance of the population's individual intrahost variants. By means of next-generation sequencing, HCV variants were obtained from sera collected at nine time points from 16 patients during the first 48 h after injection of IFN-α. IFN-resistance coefficients were calculated for individual variants using changes in their relative frequencies, and for the entire intrahost viral population using changes in viral titer. Population-wide resistance and presence of IFN-resistant variants were highly associated with pegylated IFN-α2a/ribavirin treatment outcome at week 12 (P = 3.78 × 10(-5) and 0.0114, respectively). This new method allows an accurate measurement of resistance based solely on changes in viral titer or the relative frequency of intrahost viral variants during a short observation time.

Human G9P[8] rotavirus strains circulating in Cameroon, 1999-2000: Genetic relationships with other G9 strains and detection of a new G9 subtype.

Group A rotaviruses (RV-A) are the leading cause of viral gastroenteritis in children worldwide and genotype G9P[8] is one of the five most common genotypes detected in humans. In order to gain insight into the degree of genetic variability of G9P[8] strains circulating in Cameroon, stool samples were collected during the 1999-2000 rotavirus season in two different geographic regions in Cameroon (Southwest and Western Regions). By RT-PCR, 15 G9P[8] strains (15/89=16.8%) were identified whose genomic configurations was subsequently determined by complete or partial gene sequencing. In general, all Cameroonian G9 strains clustered into current globally-spread sublineages of the VP7 gene and displayed 86.6-100% nucleotide identity amongst themselves and 81.2-99.5% nucleotide identity with global G9 strains. The full genome classification of all Cameroonian strains was G9-P[8]-I1-R1-C1-M1-A1-N1-T1-E1-H1 but phylogenetic analysis of each gene revealed that the strains were spread across 4 or more distinct lineages. An unusual strain, RVA/Human-wt/CMR/6788/1999/G9P[8], which shared the genomic constellation of other Cameroonian G9P[8] strains, contained a novel G9 subtype which diverged significantly (18.8% nucleotide and 19% amino acid distance) from previously described G9 strains. Nucleotide and amino acid alignments revealed that the 3' end of this gene is highly divergent from other G9 VP7 genes suggesting that it arose through extensive accumulation of point mutations. The results of this study demonstrate that diverse G9 strains circulated in Cameroon during 1999-2000.

CD4- and CD3-T lymphocyte reference values of immunocompetent urban and rural subjects in an African nation.

Studies on the reference values of CD4 and CD3 T cells in healthy individuals have continued to gain significance because of the importance of these immunological markers in the initiation of combination antiretroviral therapy (cART). The aim of the present study was to determine and compare the reference values of CD4 and CD3 T cells in urban and rural Nigerians who were human immunodeficiency virus (HIV), hepatitis B virus (HBV) and hepatitis C virus (HCV) negative. After ethical clearance and informed consent, 1123 subjects who met the inclusion criteria [mean age = 24.4 (± 11.2) years] were recruited in this study. Blood samples were analysed using the BD FACScount cytometer according to the manufacturer's instructions. Of the overall 1123 subjects, reference means of CD4, CD3 and CD4/CD3 ratio were 1030 ± 367, 1757 ± 609 cells/µl and 0.59 ± 0.08, respectively. Five hundred and fifty-one (49.1%) were an urban population with the mean CD4, CD3 and CD4/CD3 T cell ratio of 1032 ± 369, 1761 ± 612 cells/µl and 0.59 (±0.08), respectively. The remaining 572 (50.9%) were of a rural population with the mean CD4, CD3 and CD4/CD3 T cell ratio of 1028 ± 459, 1753 ± 958 cells/µl and 0.59 ± 0.13, respectively. Subjects with higher CD4 and CD3 T cells were more likely to be female than male (P < 0.05). There was no significant difference between the T cell values of the two populations (P > 0.05). Our findings provide new insight in the CD4 and CD3 T cell reference values of Nigerians.

Genomic characterization of human rotavirus G10 strains from the African Rotavirus Network: relationship to animal rotaviruses.

Global rotavirus surveillance has led to the detection of many unusual human rotavirus (HRV) genotypes. The aim of this study was to elucidate the genetic and evolutionary relationships of short fragments of all 11 gene segments of G10 HRV strains identified in West Africa through the African Rotavirus Network (ARN) system. During 1998-2004 surveillance within the ARN, we identified 5 G10 P[8] HRV strains. Fragments of all 11 gene segments of these G10 strains were sequenced. Phylogenetic and sequence analyses of each gene segment revealed high nucleotide similarities amongst the ARN strains (97-100%) except in the case of the VP1(85-96%) and NSP2 genes (87.8-99.7%) where some strains were divergent. All genes of the ARN strains were classified as Wa-like (genotype 1) with the exception of their VP7 gene of all strains (genotype G10) and the VP6 gene of a single strain, 6755/2002/ARN (DS-1 like, genotype 2). While classified as Wa-like, the NSP2 genes of four of the ARN strains occupied a distinct sub-lineage related to simian strain Tuch, while the NSP2 of strain 6755/2002/ARN and NSP5 genes of all strains were closely related to the cognate genes of both human and animal strains belonging to the Wa-like genogroup. Although these findings help to elucidate the evolution of ARN G10 strains, additional sequence studies of cognate animal rotavirus genes are needed to determine irrefutably the specific origin of those genes relative to both human and animal rotavirus strains.

Detection of a new subgenotype of hepatitis B virus genotype A in Cameroon but not in neighbouring Nigeria.

To further investigate the genetic diversity of hepatitis B virus (HBV) genotype A in Africa, we analysed 263 HBV strains from Nigeria (n=163) and Cameroon (n=100). Phylogenetic analysis of S fragment sequences attributed 175 strains (66.5%) to genotype E and 88 (33.5%) to genotype A. In Cameroon, genotype A strains were the most prevalent (79/100, 79.0%), whereas, in Nigeria, genotype E was highly dominant (154/163, 94.5%). The genotype A strains grouped with reference strains of subgenotype A3 (n=8), the provisional subgenotype A5 (n=43), a recently reported new variant from Rwanda (n=35), or as outliers (n=2). Ten complete genome sequences obtained from strains that clustered with the new variant from Rwanda formed a separate group supported by a bootstrap value of 96. The between-group distance to other potential or recognized subgenotypes of genotype A was at least 3.81%. Thus, the new group of strains could be considered as a new subgenotype of HBV genotype A, tentatively named 'A7'. Interestingly, the 'A7' strains from Rwanda and Cameroon showed an interspersed clustering, but essentially no other (sub)genotypes were shared between the two countries, suggesting that 'A7' may have evolved in a yet unknown place and may have only relatively recently spread to Rwanda and Western Cameroon. Strains attributed to provisional subgenotype A5 were found for the first time in Cameroon (n=36) and Central Nigeria (n=2), indicating that A5 is more widespread than previously thought.

Coordinated evolution of the hepatitis B virus polymerase.

The detection of compensatory mutations that abrogate negative fitness effects of drug-resistance and vaccine-escape mutations indicates the important role of epistatic connectivity in evolution of viruses, especially under the strong selection pressures. Mapping of epistatic connectivity in the form of coordinated substitutions should help to characterize molecular mechanisms shaping viral evolution and provides a tool for the development of novel anti-viral drugs and vaccines. We analyzed coordinated variation among amino acid sites in 370 the hepatitis B virus (HBV) polymerase sequences using Bayesian networks. Among the HBV polymerase domains the spacer domain separating terminal protein from the reverse-transcriptase domain, showed the highest network centrality. Coordinated substitutions preserve the hydrophobicity and charge of Spacer. Maximum likelihood estimates of codon selection showed that Spacer contains the highest number of positively selected sites. Identification of 67% of the domain lacking an ordered structure suggests that Spacer belongs to the class of intrinsically disordered domains and proteins whose crucial functional role in the regulation of transcription, translation and cellular signal transduction has only recently been recognized. Spacer plays a central role in the epistatic network associating substitutions across the HBV genome, including those conferring viral virulence, drug resistance and vaccine escape. The data suggest that Spacer is extensively involved in coordination of HBV evolution.

Evaluation of viral heterogeneity using next-generation sequencing, end-point limiting-dilution and mass spectrometry.

Hepatitis C Virus sequence studies mainly focus on the viral amplicon containing the Hypervariable region 1 (HVR1) to obtain a sample of sequences from which several population genetics parameters can be calculated. Recent advances in sequencing methods allow for analyzing an unprecedented number of viral variants from infected patients and present a novel opportunity for understanding viral evolution, drug resistance and immune escape. In the present paper, we compared three recent technologies for amplicon analysis: (i) Next-Generation Sequencing; (ii) Clonal sequencing using End-point Limiting-dilution for isolation of individual sequence variants followed by Real-Time PCR and sequencing; and (iii) Mass spectrometry of base-specific cleavage reactions of a target sequence. These three technologies were used to assess intra-host diversity and inter-host genetic relatedness in HVR1 amplicons obtained from 38 patients (subgenotypes 1a and 1b). Assessments of intra-host diversity varied greatly between sequence-based and mass-spectrometry-based data. However, assessments of inter-host variability by all three technologies were equally accurate in identification of genetic relatedness among viral strains. These results support the application of all three technologies for molecular epidemiology and population genetics studies. Mass spectrometry is especially promising given its high throughput, low cost and comparable results with sequence-based methods.

What factors determine the severity of hepatitis A-related acute liver failure?

The reason(s) that hepatitis A virus (HAV) infection may progress infrequently to acute liver failure are poorly understood. We examined host and viral factors in 29 consecutive adult patients with HAV-associated acute liver failure enrolled at 10 sites participating in the US ALF Study Group. Eighteen of twenty-four acute liver failure sera were PCR positive while six had no detectable virus. HAV genotype was determined using phylogenetic analysis and the full-length genome sequences of the HAV from a cute liver failure sera were compared to those from self-limited acute HAV cases selected from the CDC database. We found that rates of nucleotide substitution did not vary significantly between the liver failure and non-liver failure cases and there was no significant variation in amino acid sequences between the two groups. Four of 18 HAV isolates were sub-genotype IB, acquired from the same study site over a 3.5-year period. Sub-genotype IB was found more frequently among acute liver failure cases compared to the non-liver failure cases (chi-square test, P < 0.01). At another centre, a mother and her son presented with HAV and liver failure within 1 month of each other. Predictors of spontaneous survival included detectable serum HAV RNA, while age, gender, HAV genotype and nucleotide substitutions were not associated with outcome. The more frequent appearance of rapid viral clearance and its association with poor outcomes in acute liver failure as well as the finding of familial cases imply a possible host genetic predisposition that contributes to a fulminant course. Recurrent cases of the rare sub-genotype IB over several years at a single centre imply a community reservoir of infection and possible increased pathogenicity of certain infrequent viral genotypes.

Robust hepatitis B virus genotyping by mass spectrometry.

Genotyping of hepatitis B virus (HBV) is important for tracking HBV infections, prognosticating the development of severe liver disease, and predicting outcomes of therapy. Current genotyping methods can be laborious and costly and rely on subjective data interpretation. To identify less expensive but equally reliable alternatives, we compared "gold standard" sequencing to a novel mass spectrometry approach. Sera from individuals with acute or chronic HBV infection (n = 756), representing all genotypes, were used to PCR amplify the HBV S gene. All amplicons were subjected to base-specific cleavage and matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS). The resulting mass peak patterns were used to identify HBV genotype by automated comparison to peak patterns simulated from reference sets of HBV sequences of known genotypes. The MALDI-TOF MS data and phylogenetic analysis of HBV sequences produced completely concordant results. Several parameters such as genetic relatedness of tested HBV variants to the reference set, chronic infections, and the quality of PCR products can lower the MS score but never affected the accuracy of the genotype call. This new streamlined MS-based method provides for rapid and accurate HBV genotyping, produces automated data reports, and is therefore suitable for routine use in diagnostic settings.

Quantification of human immunodeficiency virus-1 viral load using nucleic acid sequence-based amplification (NASBA) in north central Nigeria.

BACKGROUND: Viral load (VL) quantification is considered an integral part of the standard care in human immunodeficiency virus (HIV) infected individuals but in Nigeria as in most of sub-Saharan Africa, this has not reached the majority ofpatients. METHODS: We report the first field application of the NucliSens EasyQ HIV-1 platform for the real time quantification of HIV-1 VL combining NASBA amplification and real time detection with molecular beacons among HIV-1 infected individuals in north central Nigeria where the predominant HIV-1 subtypes are CRF02_AG and G. CD4+ counts were enumerated using a fluorescence-activated cell sorter system. RESULTS: Of one hundred and forty nine (n=149) plasma sample from patients with mean age of 32 years and made up of 77 males and 72 females, fifty {n=50 (37.9%); 28 males and 22 females} had VLs below the lower detection limit (LDL=25 IU/ml) set by the assay while eighty-two {n=82 (62.1%); 39 males and 43 females} had VL levels above the LDL. Furthermore, 13 of 82 (15.9%) patients with viral loads above the LDL had VLs between 26-1000 IU/ml while 69 (84.1%) had VLs of 1001-2,400,000 IU/ml. 17 (11.4%) of the samples could not be analyzed due to poor viral amplification. Among individuals with both CD4+ and VL results (n=56), those with CD4+ of 1-418 cell/microl presented with higher VL usually above 45,000 IU/ml when compared with those with CD4+ of over 500 cell/microl. CONCLUSION: Our findings highlight the pattern, usefulness and feasibility ofVL quantification by NucliSens EasyQ in monitoring HIV-1 patients in Nigeria.

Phylogenetic analysis of human parvovirus b19 sequences from eleven different countries confirms the predominance of genotype 1 and suggests the spread of genotype 3b.

Phylogenetic analysis of 166 human parvovirus B19 sequences from 11 different countries attributed 91.57% to genotype 1, 5.42% to genotype 3b, and 3.01% to genotype 3a. Very similar viruses of genotype 1 circulated widely in Europe and Israel. Genotype 3b seems to show an increasing spread outside of Africa.

Inverted CD4+/CD8+ ratio associated with AIDS event and death in HIV-1 infected individuals in Nasarawa State, Nigeria.

The current guidelines for the use of antiretroviral therapy in Nigeria places emphasis on the use of CD4+ enumeration to take decision of initiating antiretroviral therapy and HIV disease monitoring. CD4+ counts are known to be inherently inconsistent and therefore could be misleading. This study was undertaken to analyze the CD4+/CD8+ ratio vis-à-vis CD4+ in HIV-1 infected individual in North Central Nigeria and to correlate these immunological parameters to AIDS event and death in relation to gender and age of patients. Cell counts were carried out using a Fluorescence Activated Cell Sorter (FACS) that quantifies CD4+ and CD8+ T lymphocytes as absolute numbers of lymphocytes per microL of blood and the CD4+/CD8+ T lymphocyte ratio recorded in an automated fashion. A total of 290 HIV-1 positive persons were enrolled for this study. The median CD4+/CD8+ ratio were 0.05, 0.27, 0.64 in patients with CD4+ counts of < 50, 51-200, > 350 respectively. CD4+/ CD8+ of 0.05 and 0.27 were corresponding predictors of AIDS-related event and death. Patients with > 0.64 are predictive of better disease prognosis and low progression to AIDS. The CD4+/CD8+ were minimally higher in female patients with a median CD4+/CD8 ratio of 0.27. The age distribution of our patients at point of first entry was not found to influence CD4+/CD8+ ratios. These findings provide basic and critical CD4+/CD8+ cut-off values in predicting HIV disease progression and an alternative to absolute CD4+ counts at predicting the onset of HIV related disease. These data are useful to determine when intervention with antiretroviral therapy is needed and to determine the likelihood of virological failure.

High prevalence of hepatitis B virus among female sex workers in Nigeria.

Hepatitis B virus (HBV) infection is endemic in Nigeria and constitutes a public health menace. The prevalence of HBV infection in many professional groups has been described in Nigeria. However, literature on HBV infection among female sex workers (FSW) in Nigeria is scanty. FSW in Nigeria are not subjected to a preventive control of HBV infection. This study assesses the extent of spread of HBV among FSW in Nigeria. Seven hundred and twenty (n = 720) FSW (mean age = 26.7 years) were tested for hepatitis B surface antigen (HBsAg) by a double antibody sandwich ELISA method. The overall HBV prevalence among the FSW was 17.1%. FSWs between the ages of 31-35 year (20.5%) and those with 'age-at-first-sex' below 10 years of age (28%) were most affected. This high prevalence of a vaccine preventable disease is unacceptable, therefore, vaccination of this high risk HBV reservoir group should be considered worthwhile.

High prevalence of hepatitis B virus among female sex workers in Nigeria / Alta prevalência de hepatite pelo vírus B entre trabalhadoras do sexo feminino na Nigéria

Hepatitis B virus (HBV) infection is endemic in Nigeria and constitutes a public health menace. The prevalence of HBV infection in many professional groups has been described in Nigeria. However, literature on HBV infection among female sex workers (FSW) in Nigeria is scanty. FSW in Nigeria are not subjected to a preventive control of HBV infection. This study assesses the extent of spread of HBV among FSW in Nigeria. Seven hundred and twenty (n = 720) FSW (mean age = 26.7 years) were tested for hepatitis B surface antigen (HBsAg) by a double antibody sandwich ELISA method. The overall HBV prevalence among the FSW was 17.1 percent. FSWs between the ages of 31-35 year (20.5 percent) and those with 'age-at-first-sex' below 10 years of age (28 percent) were most affected. This high prevalence of a vaccine preventable disease is unacceptable, therefore, vaccination of this high risk HBV reservoir group should be considered worthwhile.

A hepatite pelo vírus B (HBV) é infecção endêmica na Nigéria e constitui problema de saúde pública. A prevalência da infecção HBV em muitos grupos profissionais foi descrito na Nigéria. No entanto, a literatura da infecção HBV entre trabalhadoras do sexo feminino (FSW) na Nigéria é escasso. FSW na Nigéria não são submetidas a um controle preventivo de infecção de HBV. Este estudo avalia a extensão da disseminação de HBV entre FSW na Nigéria. Setecentos e vinte (n = 720) FSW (média de idade = 26,7 anos) foram testadas para antígeno de superfície da hepatite B (HBsAg) pelo método ELISA usando sandwich de duplos anticorpos. A prevalência total de HBV entre o FSW foi 17,1 por cento. FSWs entre as idades de 31-35 anos (20,5 por cento) e abaixo de 10 anos de idade (28 por cento) foram mais afetadas. Esta alta prevalência de doença evitável pela vacinação é inaceitável, portanto, vacinação deste grupo de alto risco de HBV deve ser considerada fundamental.

Human T-cell lymphotropic virus in a population of pregnant women and commercial sex workers in South Western Nigeria.

BACKGROUND: Over 20 million persons are infected with HTLV-I/II globally. The virus is endemic in Africa and it is also transmitted sexually. Continued identification of high risk groups is important for the control of the disease. OBJECTIVES: To determine the prevalence of HTLV infection amongst two highly sexually active groups, pregnant women and CSWs in South Western Nigeria. METHODS: Serum samples were tested for the presence of HTLV-I/II antibodies using the Vironostika HTLV-I/II micro ELISA system. RESULTS: A total of 364 serum samples collected from pregnant women, commercial sex worker (CSW) and secondary school students (control group) from Ibadan. While only 4 (5.1%) of 78 secondary school students (average age: 13 years) were reactive for HTLV infection, 20 (16.7%) of 120 pregnant women (average age: 26 years) and 38 (22.9%) of 166 CSWs (average age: 23 years) were found to have antibodies against HTLV in their sera. The results of this study thus show that HTLV infection is active in the population although higher in pregnant women (although not statistically significant) and CSWs (p>0.05). Pregnant women and CSWs are therefore at a higher risk of HTLV transmission than other members of the population. CONCLUSION: Routine screening for HTLV infection may go a long way to understanding the epidemiology of HTLV infection in Nigeria and subsequently provide tools for its prevention and control.

The role of triple infection with hepatitis B virus, hepatitis C virus, and human immunodeficiency virus (HIV) type-1 on CD4+ lymphocyte levels in the highly HIV infected population of North-Central Nigeria.

We set out to determine the seroprevalence of hepatitis B and C among human immunodeficiency virus type-1 (HIV-1) infected individuals in North-Central Nigeria to define the influence of these infections on CD4+ lymphocytes cells among our patients as access to antiretroviral therapy improves across the Nigerian nation. The CD4+ values of 180 confirmed HIV-1 infected individuals were enumerated using a superior fluorescence-activated cell sorter system. These patients were tested for the presence of hepatitis B surface antigen and anti-hepatitis C virus (HCV) using third generation enzyme-linked immunosorbent assays. Fifty (27.8%) patients had active hepatitis B virus (HBV) infection while 33 (18.3%) tested positive for anti-HCV antibody. Of these infections, 110 (61.1%), 37 (20.6%), and 20 (11.1%) had HIV only, HBV/HIV-only, and HCV/HIV-only respectively. A HBV/HCV/HIV coinfection prevalence of 7.2% (13 patients) was recorded. Patients coinfected with HIV/HBV/HCV appeared to have lower CD4+ counts (mean = 107 cells/microl; AIDS defining) when compared to HBV/HIV-only (mean = 377 cells/microl), HCV/HIV-only (mean = 373 cells/microl) and patients with mono HIV infection (mean = 478 cells/microl). Coinfection with HBV or HCV is relatively common among HIV-infected patients in Nigeria and should be a big consideration in the initiation and choice of therapy.

The role of triple infection with hepatitis B virus, hepatitis C virus, and human immunodeficiency virus (HIV) type-1 on CD4+ lymphocyte levels in the highly HIV infected population of North-Central Nigeria

We set out to determine the seroprevalence of hepatitis B and C among human immunodeficiency virus type-1 (HIV-1) infected individuals in North-Central Nigeria to define the influence of these infections on CD4+ lymphocytes cells among our patients as access to antiretroviral therapy improves across the Nigerian nation. The CD4+ values of 180 confirmed HIV-1 infected individuals were enumerated using a superior fluorescence-activated cell sorter system. These patients were tested for the presence of hepatitis B surface antigen and anti-hepatitis C virus (HCV) using third generation enzyme-linked immunosorbent assays. Fifty (27.8 percent) patients had active hepatitis B virus (HBV) infection while 33 (18.3 percent) tested positive for anti-HCV antibody. Of these infections, 110 (61.1 percent), 37 (20.6 percent), and 20 (11.1 percent) had HIV only, HBV/HIV-only, and HCV/HIV-only respectively. A HBV/HCV/HIV coinfection prevalence of 7.2 percent (13 patients) was recorded. Patients coinfected with HIV/HBV/HCV appeared to have lower CD4+ counts (mean = 107 cells/æl; AIDS defining) when compared to HBV/HIV-only (mean = 377 cells/æl), HCV/HIV-only (mean = 373 cells/æl) and patients with mono HIV infection (mean = 478 cells/æl). Coinfection with HBV or HCV is relatively common among HIV-infected patients in Nigeria and should be a big consideration in the initiation and choice of therapy.

Hepatitis B surface antigen (HbsAg) in the sera of medical, nursing and microbiology students in Ibadan, Nigeria.

A total of 331 serum samples collected from medical students, student nurses, microbiology students, and patients presenting with Pyrexia of Unknown Origin (PUO) were tested for the presence of Hepatitis B surface Antigen (HbsAg). While only seven (14.0%) of 50 microbiology students (mean age 24.0 years) tested positive for HbsAg, six (6.7%) of 89 student nurses (mean age 21.6 years) and 13 (13.5%) of 95 medical students (mean age 24.3 years) in the clinical phase of their study were found to have HbsAg in their sera. Also, 10 (10.3%) of 97 patients with PUO (mean age 25.4 years), a group of patients from whom medical personnel are most likely to often collect blood for laboratory studies, were found to have HbsAg in their sera. No significant difference was found in the prevalence of HbsAg among the different groups examined in this study (P>0.05). The result of the study thus shows that medical and nursing students, unlike what is known for practising nurses, physicians and surgeons are not at a higher risk of HBV transmission than students of botany and microbiology. Likewise, patients with PUO do not constitute a group that is more likely to transmit HBV to medical personnel than other groups of patients. Vaccination against hepatitis B virus during the early period of medical and nursing training may therefore go a long way to reduce the high prevalence of hepatitis B virus infection previously reported among practising health personnel in Nigeria.