RESUMO
Background: The international impact, rapid widespread transmission, and reporting delays during the 2014 Ebola outbreak in West Africa highlighted the need for a global, centralized database to inform outbreak response. The World Health Organization and Emerging and Dangerous Pathogens Laboratory Network addressed this need by supporting the development of a global laboratory database. Methods: Specimens were collected in the affected countries from patients and dead bodies meeting the case definitions for Ebola virus disease. Test results were entered in nationally standardized spreadsheets and consolidated onto a central server. Results: From March 2014 through August 2016, 256343 specimens tested for Ebola virus disease were captured in the database. Thirty-one specimen types were collected, and a variety of diagnostic tests were performed. Regular analysis of data described the functionality of laboratory and response systems, positivity rates, and the geographic distribution of specimens. Conclusion: With data standardization and end user buy-in, the collection and analysis of large amounts of data with multiple stakeholders and collaborators across various user-access levels was made possible and contributed to outbreak response needs. The usefulness and value of a multifunctional global laboratory database is far reaching, with uses including virtual biobanking, disease forecasting, and adaption to other disease outbreaks.
Assuntos
Bancos de Espécimes Biológicos/normas , Bases de Dados Factuais/normas , Surtos de Doenças/estatística & dados numéricos , Ebolavirus/fisiologia , Doença pelo Vírus Ebola/epidemiologia , Doença pelo Vírus Ebola/virologia , África Ocidental/epidemiologia , Saúde Global , Humanos , Laboratórios , Organização Mundial da SaúdeRESUMO
BACKGROUND: The goal of selecting a healthy blood donor is to safeguard donors and reduce the risks of infections and immunologic complications for recipients. STUDY DESIGN AND METHODS: To evaluate the blood donor selection process, a survey was conducted in 28 blood transfusion centers located in 15 francophone African countries. Data collected included availability of blood products, risk factors for infection identified among blood donor candidates, the processing of the information collected before blood collection, the review process for the medical history of blood donor candidates, and deferral criteria for donor candidates. RESULTS: During the year 2009, participating transfusion centers identified 366,924 blood donor candidates. A mean of 13% (range, 0%-36%) of the donor candidates were excluded based solely on their medical status. The main risk factors for blood-borne infections were having multiple sex partners, sexual intercourse with occasional partners, and religious scarification. Most transfusion centers collected this information verbally instead of having a written questionnaire. The topics least addressed were the possible complications relating to the donation, religious scarifications, and history of sickle cell anemia and hemorrhage. Only three centers recorded the temperature of the blood donors. The deferral criteria least reported were sickle cell anemia, piercing, scarification, and tattoo. CONCLUSIONS: The medical selection process was not performed systemically and thoroughly enough, given the regional epidemiologic risks. It is essential to identify the risk factors specific to francophone African countries and modify the current medical history questionnaires to develop a more effective and relevant selection process.
Assuntos
Doadores de Sangue/estatística & dados numéricos , Transfusão de Sangue/estatística & dados numéricos , Seleção do Doador/métodos , Seleção do Doador/normas , Adulto , África , Bancos de Sangue/estatística & dados numéricos , Feminino , Humanos , MasculinoRESUMO
BACKGROUND AND OBJECTIVE: The high prevalence of numerous transfusion-transmitted infectious diseases such as HIV, HBV, HCV and syphilis in sub-Saharan Africa affects blood safety for transfusion recipients. The aim of this study was to evaluate the prevalence and incidence of transfusion-transmissible infectious diseases among blood donors in Burkina Faso. METHODS: A retrospective study of blood donors' records from January to December 2009 was conducted. Prevalence and incidence of viral infections were calculated among repeat and first-time blood donors. RESULTS: Of the total of 31405 first-time volunteer blood donors in 2009, 24.0% were infected with at least one pathogen and 1.8% had serological evidence of multiple infections. The seroprevalence of HIV, HBV, HCV and syphilis in first-time volunteer donors was 1.8%, 13.4%, 6.3% and 2.1%, respectively. In 3981 repeat donors, the incidence rate was 3270.2, 5874.1 and 6784.6 per 100000 donations for anti-HIV-1, HBsAg and anti-HCV, respectively. These numbers varied significantly according to populations where blood is collected and blood centres in Burkina Faso. CONCLUSION: The relatively high prevalence of viral markers in first-time volunteers and remarkably high incidence of infections in repeat donors raise concerns regarding the safety of these donors and suggest that implementation of NAT might significantly improve the situation.
Assuntos
Anticorpos Antivirais/sangue , Doenças Transmissíveis/sangue , Infecções por HIV/transmissão , Hepatite B/transmissão , Hepatite C/transmissão , Sífilis/transmissão , Reação Transfusional , Adolescente , Adulto , Idoso , Biomarcadores/sangue , Doadores de Sangue/estatística & dados numéricos , Burkina Faso/epidemiologia , Doenças Transmissíveis/epidemiologia , Feminino , Infecções por HIV/sangue , Infecções por HIV/epidemiologia , Hepatite B/sangue , Hepatite B/epidemiologia , Antígenos de Superfície da Hepatite B/sangue , Hepatite C/sangue , Hepatite C/epidemiologia , Humanos , Incidência , Masculino , Pessoa de Meia-Idade , Prevalência , Estudos Soroepidemiológicos , Sífilis/sangue , Sífilis/epidemiologia , Adulto JovemAssuntos
Anticorpos Antivirais/sangue , Doadores de Sangue , Vírus da Hepatite E/genética , Hepatite E/epidemiologia , RNA Viral/sangue , Adolescente , Adulto , Idoso , Burkina Faso/epidemiologia , Feminino , Hepatite E/imunologia , Hepatite E/virologia , Vírus da Hepatite E/classificação , Vírus da Hepatite E/isolamento & purificação , Humanos , Imunoglobulina G/sangue , Imunoglobulina M/sangue , Masculino , Pessoa de Meia-Idade , Estudos SoroepidemiológicosRESUMO
Human parvovirus 4 infections are primarily associated with parenteral exposure in western countries. By ELISA, we demonstrate frequent seropositivity for antibody to parvovirus 4 viral protein 2 among adult populations throughout sub-Saharan Africa (Burkina Faso, 37%; Cameroon, 25%; Democratic Republic of the Congo, 35%; South Africa, 20%), which implies existence of alternative transmission routes.
Assuntos
Anticorpos Antivirais/sangue , Infecções por Parvoviridae/epidemiologia , Infecções por Parvoviridae/virologia , Parvovirus/imunologia , Adolescente , Adulto , África Subsaariana/epidemiologia , Idoso , Burkina Faso/epidemiologia , Camarões/epidemiologia , Proteínas do Capsídeo/imunologia , Criança , República Democrática do Congo/epidemiologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , África do Sul/epidemiologia , Adulto JovemRESUMO
BACKGROUND: In Africa where blood-borne agents are highly prevalent, cheaper and feasible alternative strategies for blood donations testing are specifically required. STUDY DESIGN AND METHODS: From May to August 2002, 500 blood donations from Burkina Faso were tested for hepatitis B surface antigen (HBsAg), human immunodeficiency virus (HIV), syphilis, and hepatitis C virus (HCV) according to two distinct strategies. The first strategy was a conventional simultaneous screening of these four blood-borne infectious agents on each blood donation by using single-marker assays. The second strategy was a sequential screening starting by HBsAg. HBsAg-nonreactive blood donations were then further tested for HIV. If nonreactive, they were further tested for syphilis. If nonreactive, they were finally assessed for HCV antibodies. The accuracy and cost-effectiveness of the two strategies were compared. RESULTS: By using the simultaneous strategy, the seroprevalences of HBsAg, HIV, syphilis, and HCV among blood donors in Ouagadougou were estimated to be 19.2, 9.8, 1.6, and 5.2%. No significant difference of HIV, syphilis, and HCV prevalence rates was observed by using the sequential strategy (9.2, 1.9, and 4.7%, respectively). Whatever the strategy used, 157 blood donations (31.4%) were found to be reactive for at least one transfusion-transmissible agent and were thus discarded. The sequential strategy allowed a cost decrease of euro 908.6, compared to the simultaneous strategy. Given that approximately there are 50,000 blood donations annually in Burkina Faso, the money savings reached potentially euro 90,860. CONCLUSIONS: In resource-limited settings, the implementation of a sequential strategy appears as a pragmatic solution to promote safe blood supply and ensure sustainability of the system.
Assuntos
Doadores de Sangue , Transfusão de Sangue/economia , Infecções por HIV/prevenção & controle , Hepatite B/prevenção & controle , Hepatite C/prevenção & controle , Sífilis/prevenção & controle , África Subsaariana , Burkina Faso , Infecções por HIV/transmissão , Hepatite B/transmissão , Hepatite C/transmissão , Humanos , Sífilis/transmissão , Reação TransfusionalRESUMO
BACKGROUND: Following World Health Organization recommendations that a quality control (QC) system be implemented in African blood centers, a pilot study of the performance of human immunodeficiency virus antibody (anti-HIV), hepatitis B surface antigen (HBsAg), and hepatitis C virus antibody (anti-HCV) testing by several Sub-Saharan African blood centers was initiated. STUDY DESIGN AND METHODS: A reference laboratory sent a panel of 25 samples to six African blood center laboratories. The panel included eight negative samples; four anti-HIV-1, one anti-HIV-2, four anti-HCV, and five HBsAg-positive samples; and three samples consisting of mixtures of two sera to mimic coinfections. Sensitivity, specificity, and overall quality (correct positive or negative status) scores were calculated. RESULTS: From the 21 sets of results obtained (seven for each virus), eight were from rapid tests (two for HIV, three for HBV, and three for HCV) and 13 were from enzyme immunoassays (EIAs; all HIV EIAs were antigen/antibody combination assays). Overall assay sensitivity was 98% for HIV, 75% for HBV, and 88% for HCV; agreement between blood centers using the same assay was good. Sensitivity of rapid tests was notably poorer than EIAs, with overall sensitivity quality scores of 64.5% for rapid tests (20% for HBsAg rapid tests) compared to 100% for EIAs. The overall specificity quality scores were 98.3 and 94.5% for EIAs and rapid tests, respectively. CONCLUSIONS: This pilot QC study organized for blood centers of Sub-Saharan Africa showed the feasibility of the approach despite some logistic constraints. Although interlaboratory variability was small, the poor performance of rapid tests, especially for HBsAg, raises policy questions about their use as the only screening assay.
Assuntos
Bancos de Sangue , Anticorpos Anti-HIV/sangue , Antígenos de Superfície da Hepatite B/sangue , Anticorpos Anti-Hepatite C/sangue , Segurança , Análise e Desempenho de Tarefas , África , Transfusão de Sangue , Humanos , Técnicas Imunoenzimáticas/métodos , Projetos Piloto , Controle de Qualidade , Sensibilidade e EspecificidadeRESUMO
BACKGROUND: The importance of blood safety in public health was recognized long ago, and data are essential to plan strategies to improve the status. This study aims to obtain data on blood donor and blood donation characteristics that would complement blood safety data from national and international organizations. MATERIALS AND METHODS: A questionnaire was sent to seven Francophone countries (Burkina Faso, Cameroon, Congo, Ivory Coast, Mali, Niger, and Rwanda) and was structured to obtain objective data on blood donors and donated blood and in administrative and technical organization. RESULTS: The results reflect a poor level of organization of blood transfusion centers in large regions of the African continent, insufficient supply of blood products, high prevalence of transfusion-transmitted infections, limited financial resources, a lack of well-trained personnel, and cultural obstacles. Six countries had less than 50% of their personnel trained in transfusion medicine. Only one country had the entire standard operating procedure written. Female donors represented less than 30% of the donors and the range of percentage of hepatitis B found in donors was 2.76% to 18.96%. CONCLUSION: The inclusion of these regions in future blood safety surveys and in the development of national blood transfusion programs is essential and will undoubtedly require the assistance of international organizations.
Assuntos
Doadores de Sangue , Transfusão de Sangue , Seleção do Doador , Inquéritos e Questionários , África Subsaariana/epidemiologia , Patógenos Transmitidos pelo Sangue , Educação Médica Continuada/métodos , Feminino , Hepatite B/epidemiologia , Humanos , Infecções/epidemiologia , Masculino , Prevalência , Fatores SexuaisRESUMO
BACKGROUND: Laboratory-enhanced surveillance is critical for rapidly detecting the potential re-emergence of Ebola virus disease. Rapid diagnostic tests (RDT) for Ebola antigens could expand diagnostic capacity for Ebola virus disease. OBJECTIVES: The Guinean National Coordination for Ebola Response conducted a pilot implementation to determine the feasibility of broad screening of patients and corpses with the OraQuick® Ebola RDT. METHODS: The implementation team developed protocols and trained healthcare workers to screen patients and corpses in Forécariah prefecture, Guinea, from 15 October to 30 November 2015. Data collected included number of consultations, number of fevers reported or measured, number of tests performed for patients or corpses and results of confirmatory RT-PCR testing. Data on malaria RDT results were collected for comparison. Feedback from Ebola RDT users was collected informally during supervision visits and forums. RESULTS: There were 3738 consultations at the 15 selected healthcare facilities; 74.6% of consultations were for febrile illness. Among 2787 eligible febrile patients, 2633 were tested for malaria and 1628 OraQuick® Ebola RDTs were performed. A total of 322 OraQuick® Ebola RDTs were conducted on corpses. All Ebola tests on eligible patients were negative. CONCLUSIONS: Access to Ebola testing was expanded by the implementation of RDTs in an emergency situation. Feedback from Ebola RDT users and lessons learned will contribute to improving quality for RDT expansion.
RESUMO
INTRODUCTION: In most developing countries, Cytomegalovirus (CMV), Epstein Barr virus (EBV) and Herpes virus 6 (HHV-6) are not diagnosed in blood donors. The aim of this study is to determine the prevalence of these viruses in blood donors from the city of Ouagadougou, Burkina Faso. METHODS: The study included 198 blood donors of the Regional Blood Transfusion Centre of Ouagadougou. Multiplex real time PCR was used to diagnose the three viruses. Statistical analysis was performed with the software EpiInfo version 6 and SPSS version 17. P values ≤ 0.05 were considered significant. RESULTS: Of 198 samples tested, 18 (9.1%) were positive to at least one of the three viruses. In fact, 10 (5.1%) were positive for EBV, 10 (5.1%) positive for CMV and 12 (6.1%) positive for HHV-6. Viral infections were higher in women than in men, EBV (8,6% versus 4.3%), CMV (8.6% versus 3.7%) and HHV-6 (11.4% versus 4.9%). EBV / CMV / HHV-6 co-infection was found in 3.5% (7/198) of blood donors. CONCLUSION: The prevalence recorded in this study is low compared to those found in previous studies from the sub-region among blood donors. The molecular diagnostic test used in our study could explain the differences with previous studies.
Assuntos
Doadores de Sangue , Infecções por Citomegalovirus/diagnóstico , Infecções por Vírus Epstein-Barr/diagnóstico , Infecções por Roseolovirus/diagnóstico , Adolescente , Adulto , Burkina Faso/epidemiologia , Coinfecção , Estudos Transversais , Citomegalovirus/isolamento & purificação , Infecções por Citomegalovirus/epidemiologia , Infecções por Vírus Epstein-Barr/epidemiologia , Feminino , Herpesvirus Humano 4/isolamento & purificação , Herpesvirus Humano 6/isolamento & purificação , Humanos , Masculino , Técnicas de Diagnóstico Molecular/métodos , Prevalência , Reação em Cadeia da Polimerase em Tempo Real , Infecções por Roseolovirus/epidemiologia , Distribuição por Sexo , Adulto JovemRESUMO
BACKGROUND: Hepatitis C virus (HCV) is responsible for about 900 deaths every year in Burkina Faso. In this country, serological screening for hepatitis B and C viruses is only carried out systematically among blood donors. The aim of this study was to determine the prevalence and genotypes of HCV among blood donors using reverse transcription polymerase chain reaction (PCR) and real-time PCR, respectively. MATERIALS AND METHODS: Serum samples were screened for antibodies to HCV using an enzyme-linked immunosorbent assay (ARCHITECT-i1000SR-ABBOTT). All the reactive samples for HCV antibodies were re-tested using a second enzyme-linked immunosorbent assay (Bio-Rad, Marnes la Coquette, France) for confirmation. RNA was detected in all the reactive samples for antibodies to HCV. HCV RNA positive samples were genotyped using the HCV Real-TM Genotype kit (Sacace Biotechnologies, Italy). RESULTS: Among 2,200 blood donors, the prevalences of antibodies to HCV and viral RNA were 4.4% (95% confidence interval=3.5-5.3) and 1.5% (95% confidence interval=1.0-2.0), respectively. Among HCV RNA carriers, genotyping showed that HCV genotypes 2 and 3 were the most prevalent as they were detected in 18 (56.3%) and 5 (15.6%) individuals, respectively. HCV genotypes 1a and 4 were the least frequent among the blood donors. HCV mixed genotypes 2/3 and 2/4 were also detected among the blood donors. CONCLUSION: The prevalence of HCV found in this study is lower than previously reported prevalences. Large-scale studies are needed to obtain a better picture of the molecular epidemiology of HCV in Burkina Faso.
Assuntos
Doadores de Sangue , Hepacivirus/genética , Hepatite C/virologia , Viremia/virologia , Adolescente , Adulto , Idoso , Bancos de Sangue , Burkina Faso/epidemiologia , Comorbidade , Seleção do Doador , Ensaio de Imunoadsorção Enzimática , Feminino , Genótipo , Técnicas de Genotipagem , Infecções por HIV/epidemiologia , Hepacivirus/classificação , Hepacivirus/imunologia , Hepacivirus/isolamento & purificação , Hepatite B/epidemiologia , Hepatite C/sangue , Hepatite C/epidemiologia , Anticorpos Anti-Hepatite C/sangue , Humanos , Masculino , Pessoa de Meia-Idade , RNA Viral/sangue , Kit de Reagentes para Diagnóstico , Estudos Soroepidemiológicos , Sífilis/epidemiologia , Viremia/epidemiologia , Adulto JovemRESUMO
Hepatitis A virus (HAV) and hepatitis E virus (HEV) infections occur chiefly as a result of unhygienic conditions. The purpose of this study was to assess the seroprevalence of antibodies to both viruses in central Burkina Faso in the absence of a recorded hepatitis epidemic. Serum samples from 178 blood donors (131 males and 47 females) and from 189 pregnant women were collected from November 2010 to March 2012, at blood banks and medical centers in Burkina Faso. An immunochromatography test was used to screen for Anti-HAV IgM and IgG in a subgroup of 91 blood donors and 100 pregnant women. The seroprevalence of anti-HAV IgG was 14.3% [CI95, 7.1-21.4%] for all blood donors and 23% [CI95, 14.8-31.2%] for pregnant women. Anti-HEV IgG were detected using the ELISA kits Dia.pro and Wantai and were found in 19.1% [CI95, 13.3-24.9%] of the blood donors and 11.6% [CI95, 7.1-16.2%] of the pregnant women. The seroprevalences of anti-HAV and anti-HEV IgGs did not differ significantly between men and women blood donors. Anti-HAV IgM was detected in 3.3% of the blood donors and in 2% of the pregnant women. These findings for asymptomatic individuals indicate that the HAV and HEV circulate at low but significant levels. This is the first evaluation of the acute hepatitis virus burden in Burkina Faso and the underlying epidemiologic status of the population.
Assuntos
Anticorpos Antivirais/imunologia , Vírus da Hepatite A/imunologia , Hepatite A/imunologia , Vírus da Hepatite E/imunologia , Hepatite E/imunologia , Adulto , Fatores Etários , Idoso , Anticorpos Antivirais/sangue , Burkina Faso/epidemiologia , Ensaio de Imunoadsorção Enzimática , Fezes/virologia , Feminino , Hepatite A/sangue , Hepatite A/epidemiologia , Hepatite E/sangue , Hepatite E/epidemiologia , Humanos , Imunoglobulina G/sangue , Imunoglobulina G/imunologia , Imunoglobulina M/sangue , Imunoglobulina M/imunologia , Masculino , Pessoa de Meia-Idade , Gravidez , Prevalência , Estudos Soroepidemiológicos , Adulto JovemRESUMO
BACKGROUND: The high prevalence of numerous transfusion-transmitted infectious diseases such as human immunodeficiency virus (HIV), hepatitis B virus (HBV), hepatitis C virus (HCV) and syphilis in sub-Saharan Africa affects the safety of blood for recipients. This study was undertaken with the aim of determining the seroprevalence of HIV, HCV, HBV, syphilis and socio-demographic risk factors associated with blood donation in a new regional blood transfusion centre in Burkina Faso. MATERIAL AND METHODS: Sera samples were screened for hepatitis B surface antigen (HBsAg), antibodies to HCV, HIV types 1 and 2 and to Treponema pallidum using enzyme-linked immunosorbent assays and Rapid Plasma Reagin test (RPR) respectively. All the reactive samples for HIV, HBsAg, and HCV were confirmed using a second enzyme-linked immunosorbent assays. Antibodies to Treponema pallidum were confirmed with a Treponema pallidum haemagglutination test (TPHA). RESULTS: From the total of 4,520 blood donors in 2009, 1,348 (29.82%) were infected with at least one pathogen and 149 (3.30%) had serological evidence of multiple infections. The overall seroprevalence rate of HIV, HBV, HCV and syphilis was 2.21%, 14.96%, 8.69% and 3.96%, respectively. Among blood donors with multiples infections, the most common dual or triple combinations were HBsAg-HCV (1.39%), HBsAg-syphilis (0.66%) and HBsAg-HCV-syphilis (0.11%). The highest prevalences of HBsAg and HIV were found among blood donors from rural areas and in the age groups of 20-29 years and >40 years old, respectively. CONCLUSION: HBV and HCV remain the greatest threats to blood safety in Burkina Faso. Strict selection and retention of voluntary, non-remunerated low-risk blood donors are recommended to improve blood safety in the regional blood transfusion centre of Koudougou.
Assuntos
Doadores de Sangue/estatística & dados numéricos , Infecções por HIV/epidemiologia , Soroprevalência de HIV , Hepatite B/epidemiologia , Hepatite C/epidemiologia , Sífilis/epidemiologia , Adulto , Burkina Faso/epidemiologia , Feminino , Infecções por HIV/sangue , Hepatite B/sangue , Hepatite C/sangue , Humanos , Masculino , Estudos Retrospectivos , Fatores de Risco , Estudos Soroepidemiológicos , Sífilis/sangue , Adulto JovemRESUMO
In subsaharan Africa, knowledge of the organization and methods of transfusion centers, as well as blood donor characteristics, is essential in choosing strategies to improve transfusion practices and the security of blood products on this Continent. The present study was based on a analysis led in partnership with the transfusion of seven francophone African countries (Burkina-Faso, Cameroon, Congo, Ivory Cost, Mali, Niger, and Rwanda). The results showed that withstanding significant progress has been realized in the organization and safety, but much remains to be undertaken over the years to come in order to improve the organization of the centers, the providing of blood products and the infectious and immunohematologic safety. This evolution, for the moment, is limited by the financial resources, insufficient training of personnel and cultural obstacles, but will necessarily pass through the pursuit of conjugated efforts of the scientific, international and local communities.
Assuntos
Bancos de Sangue , Doadores de Sangue , Transfusão de Sangue , Administração de Instituições de Saúde , África Subsaariana , Sangue/virologia , Tipagem e Reações Cruzadas Sanguíneas , Humanos , Reação TransfusionalRESUMO
Despite recent National Immunization Days in Burkina Faso, the rural province of Houët reported >400 measles cases in 2001 (82% not vaccinated). Phylogenetic analysis of 58 measles virus field isolates plus the first sequences from the Democratic Republic of the Congo and the Republic of Congo are reported. All viruses were genotype B3, which is common in the region. In Houët, there were two geographically confined genetic variants, suggesting two independent importation events. Strain diversity in Houët (1.5%) and the Congos was limited in comparison with Ibadan, Nigeria (4.6%), where measles is endemic. Strain variability, assessed by heteroduplex mobility assay, confirmed these findings. Despite large local pools of susceptible persons even after several rounds of vaccination, the limited strain diversity suggests that parts of rural Burkina Faso may be moving from an endemic to an epidemic transmission pattern of measles virus.
Assuntos
Surtos de Doenças , Doenças Endêmicas , Vírus do Sarampo/genética , Sarampo/virologia , Adolescente , Anticorpos Antivirais/sangue , Burkina Faso/epidemiologia , Criança , Pré-Escolar , Variação Genética , Humanos , Programas de Imunização/métodos , Programas de Imunização/normas , Lactente , Sarampo/epidemiologia , Sarampo/prevenção & controle , Sarampo/transmissão , Vacina contra Sarampo/administração & dosagem , Vírus do Sarampo/isolamento & purificação , Epidemiologia Molecular , Filogenia , RNA Viral/química , RNA Viral/genética , Reação em Cadeia da Polimerase Via Transcriptase Reversa , População RuralRESUMO
Sub-Saharan Africa suffers from an excessively high endemicity of hepatitis B virus (HBV), but little is known about the prevalent genotypes. In this study, we investigated the PreS1/PreS2/S genes of 127 viruses obtained from 12 locations in Mali, Burkina Faso, Togo, Benin, Nigeria, Cameroon, and the Democratic Republic of Congo. Except for those obtained from the Cameroon HIV cohort (18/22 HBV genotype A), 96 of 105 sequences belonged to HBV genotype E (HBV/E), and viral DNA was very similar (1.67% diversity) throughout this vast HBV/E crescent, which spans 6000 km across Africa. The low diversity suggests that HBV/E may have a short evolutionary history. Considering a typical mutation rate of DNA viruses, it would take only 200 years for the strain diversity of HBV/E viruses to develop from a single introductory event. The relatively recent introduction of HBV/E into humans would also explain its conspicuous absence in the Americas, despite the forced immigration of slaves from west Africa, until the early 19th century. Infection during infancy is mostly associated with chronic carrier status, and this combination can account for the explosive spread of virtually identical viruses within a community, but whether other routes of long-range transmissions must be considered becomes an important question.