Methodology of a nationwide cross-sectional survey of prevalence and epidemiological patterns of hepatitis A, B and C infection in Brazil.

A population-based survey to provide information on the prevalence of hepatitis viral infection and the pattern of risk factors was carried out in the urban population of all Brazilian state capitals and the Federal District, between 2005 and 2009. This paper describes the design and methodology of the study which involved a population aged 5 to 19 for hepatitis A and 10 to 69 for hepatitis B and C. Interviews and blood samples were obtained through household visits. The sample was selected using stratified multi-stage cluster sampling and was drawn with equal probability from each domain of study (region and age-group). Nationwide, 19,280 households and ~31,000 residents were selected. The study is large enough to detect prevalence of viral infection around 0.1% and risk factor assessments within each region. The methodology seems to be a viable way of differentiating between distinct epidemiological patterns of hepatitis A, B and C. These data will be of value for the evaluation of vaccination policies and for the design of control program strategies.

Methodology of a nationwide cross-sectional survey of prevalence and epidemiological patterns of hepatitis A, B and C infection in Brazil / Metodologia de um estudo de inquérito nacional da prevalência e de padrõesa epidemiológicos das hepatites A, B e C no Brasil

Um inquérito de base populacional foi conduzido na população urbana de todas as capitais e do Distrito Federal no Brasil para fornecer informações sobre a prevalência de hepatites virais e fatores de risco, entre 2005 e 2009. Este artigo descreve o delineamento e a metodologia do estudo que envolveu a população com idade entre 5 e 19 anos para hepatite A e 10 a 69 anos para hepatite B e C. As entrevistas e amostras de sangue foram obtidas através de visitas domiciliares e a amostra selecionada a partir de uma amostragem estratificada em múltiplos estágios (por conglomerado) com igual probabilidade para cada domínio de estudo (região e faixa etária). Nacionalmente, 19.280 residências e ~31.000 indivíduos foram selecionados. O tamanho da amostra foi suficiente para detectar uma prevalência em torno de 0,1 por cento e para avaliar os fatores de risco por região. A metodologia apresentou-se viável para distinguir entre diferentes padrões epidemiológicos da hepatite A, B e C. Estes dados serão de valia para a avaliação das políticas de vacinação e para o desenho de estratégias de controle.

A population-based survey to provide information on the prevalence of hepatitis viral infection and the pattern of risk factors was carried out in the urban population of all Brazilian state capitals and the Federal District, between 2005 and 2009. This paper describes the design and methodology of the study which involved a population aged 5 to 19 for hepatitis A and 10 to 69 for hepatitis B and C. Interviews and blood samples were obtained through household visits. The sample was selected using stratified multi-stage cluster sampling and was drawn with equal probability from each domain of study (region and age-group). Nationwide, 19,280 households and ~31,000 residents were selected. The study is large enough to detect prevalence of viral infection around 0.1 percent and risk factor assessments within each region. The methodology seems to be a viable way of differentiating between distinct epidemiological patterns of hepatitis A, B and C. These data will be of value for the evaluation of vaccination policies and for the design of control program strategies.

Phylogeny and molecular genetic parameters of different stages of hepatitis B virus infection in patients from the Brazilian Amazon.

A fragment of 600 bp of the gene which codes for the surface antigen of hepatitis B virus (HBV) was amplified and sequenced from patients who were born in five states of the Brazilian Amazon (Amazonas, Pará, Acre, Rondônia and Tocantins). A total of 44 sequences were used for the estimation of molecular genetic parameters and phylogenetic analyses. Compared with patients who were asymptomatic, those who had acute hepatitis and chronic liver disease had higher levels of genetic variability and higher rates of nucleotide substitutions. The analysis of transition and transversion substitutions showed that transition-type substitutions predominated. In chronic liver disease carriers, transversion-type substitutions showed phylogenetic saturation. In general, all of the analyses carried out in this study showed an association between patterns of changes in molecular genetic parameters and the stage of disease progression. Phylogenetic analysis using the HKY85 model of evolution identified 41 individuals as genotype A, suggesting its predominance in the Amazon region, one individual as genotype C, and one individual closely related to genotypes E and F.

[Hepatitis C virus infection in the Amazon Brazilian region]. / Infecção pelo vírus da hepatite C na região Amazônica brasileira.

The article evaluates available scientific information concerning the prevalence and clinical characteristics of hepatitis C virus infection in the Brazilian Amazon, a know endemic area for hepatitis A, B and D viruses infection. All the information was obtained through extensive analysis of original and review articles and abstracts published in distinguished journals or in scientific meetings. In the Amazon Region, HCV infection prevalence rate in the general population varies from 1.1 to 2.4%. Among blood donators the prevalence rate varies from 0.8 to 5.9%. Pard (Eastern Amazon) and Acre (Western Amazon) State present the highest rates, 2% and 5.9%, respectively. In respect to the HCV infection prevalence rate in the risk groups, one observates high prevalence. In the Brazilian Amazon, infection by HCV seems to cope in the same way of infection in other parts of the world among the hemodialized (48.1 - 51.9%), health professionals (3.2%), HCV carriers contactants (10%) and lichen plannus patients (7.5%). There is a significant predominance of genotype 1, being sub-type 1b the most frequent. The HCV infection is similar in men and women and most of the infected are above 39 years of age. The major route of infection is parenteral and the major risk factors are blood transfusion and surgical procedures. HCV is rarely responsable for acute severe hepatitis in this region. On the other hand, of all chronic hepatitis, 22.6% are attributed to HCV in the Western Amazon and 25% in the Eastern Amazon. In the Brazilian Amazon, infection by HCV seems to cope in the same way of infection in other parts of the world.

Prevalência da infecção pelos vírus da hepatite B(VHB) e da hepatite Delta(VHD) em Lábrea, Rio Purus, Estado do Amazonas / Prevalence of the infection for the viruses of hepatitis B(VHB) and the Hepatitis Delta(VHD) in Lábrea, River Purus, been of Amazon

O presente trabalho estima a prevalência da infecção pelos vírus da hepatite B(VHB) e da hepatite Delta(VHD) na cidade de Lábrea, Estado do Amazonas, 11 anos após a introdução da vacina contra hepatite B na região. A taxa de prevalência do anti-HBc total encontrada foi de 49,9 por cento e a de portadores do antígeno de superfície do VHB(AgHBs), 3,3 por cento. A infecção pelo VHB apresenta padrão de endemicidade moderado, baixo potencial de infectividade e curso subclínico da infecção. A transmissão acontece, principalmente, entre crianas de 6 a 12 anos de idade e adultos jovens, que se infectam, provavelmente, por transmissão vertical ou horizontal familiar e por contato sexual, sob risco moderado de desenvolver formas crõnicas de hepatite. O VHD foi encontrado em 30 por cento dos indivíduos com reatividade para o AgHBs, associado a histórico de hepatite aguda e a indivíduos portadores do VHB com sinais bioquímicos de lesão hepática, demonstrando a importância da associação desses dois agentes na etiologia de doenças do fígado nessa população. O estudo identifica uma redução signitficativa - de, no mínimo, cinco vêzes - da taxa de portadores do AgHBs na comunidade, apesar de termos identificados falhas na proteçao de indivíduos suscetíveis...

Infecção pelo vírus da hepatite C na região Amazônica brasileira / Hepatitis C virus infection in the Amazon brazilian region

O artigo avalia informações científicas disponíveis sobre a prevalência e características clínicas da infecção pelo virus da hepatite C na Amazônia Brasileira, uma área sabidamente endêmica para infecção pelos vírus das hepatites A, B e D. Toda a informação foi obtida através de extensa revisão bibliográfica de artigos originais e de revisão e de resumos publicados em periódicos conceituados ou em eventos científicos. Na Região Amazônica, a taxa de prevalência de infecção por VHC na população geral varia de 1,1 a 2,4%. Entre doadores de sangue as taxas de prevalência variam de 0,8% a 5,9%. O Estado do Pará (Amazônia oriental) e do Acre (Amazônia ocidental) apresentam as maiores taxas, 2% e 5,9%, respectivamente. Com relação à prevalência da infecção pelo VHC em grupos de risco, observa-se alta prevalência entre hemodiálisados (48,1% - 51,9%), profissionais de saúde (3,2%), contactantes de portadores do VHC (10%) e pacientes com lichen plannus (7,5%). Existe uma predominância significativa do genótipo 1, com maior freqüência do subtipo 1b. A infecção pelo VHC é similar em homens e mulheres e a maioria dos infectados têm mais de 39 anos de idade. A principal via de infecção é a parenteral e os principais fatores de risco são transfusão sangüínea e procedimentos cirúrgicos. O VHC raramente é responsável por hepatite aguda grave nesta região. Por outro lado, de todas as hepatites crônicas, 22,6% são atribuídas ao VHC na Amazônia Ocidental e 25% na Amazônia Oriental. Na Amazônia Brasileira, a infecção pelo VHC parece ter o mesmo comportamento da infecção em outras partes do mundo.

The article evaluates available scientific information concerning the prevalence and clinical characteristics of hepatitis C virus infection in the Brazilian Amazon, a know endemic area for hepatitis A, B and D viruses infection. All the information was obtained through extensive analysis of original and review articles and abstracts published in distinguished journals or in scientific meetings. In the Amazon Region, HCV infection prevalence rate in the general population varies from 1.1 to 2.4%. Among blood donators the prevalence rate varies from 0.8 to 5.9%. Pará (Eastern Amazon) and Acre (Western Amazon) State present the highest rates, 2% and 5.9%, respectively. In respect to the HCV infection prevalence rate in the risk groups, one observates high prevalence In the Brazilian Amazon, infection by HCV seems to cope in the same way of infection in other parts of the world among the hemodialized (48.1 - 51.9%), health professionals (3.2%), HCV carriers contactants (10%) and lichen plannus patients (7.5%). There is a significant predominance of genotype 1, being sub-type 1b the most frequent. The HCV infection is similar in men and women and most of the infected are above 39 years of age. The major route of infection is parenteral and the major risk factors are blood transfusion and surgical procedures. HCV is rarely responsable for acute severe hepatitis in this region. On the other hand, of all chronic hepatitis, 22.6% are attributed to HCV in the Western Amazon and 25% in the Eastern Amazon. In the Brazilian Amazon, infection by HCV seems to cope in the same way of infection in other parts of the world.

[Prevalence of hepatitis B virus markers within household contacts in the State of Amazonas]. / Prevalência de marcadores para o vírus da hepatite B em contatos domiciliares no Estado do Amazonas.

The aim of our investigation was to evaluate, with a prevalence study, the modes of transmission of Hepatitis B virus (HBV), within infected subjects and their household contacts in the State of Amazon, western Brazilian Amazon. We studied 97 index cases and 258 household contacts. Out of the 258 household contacts of HBV, 51.6% had serological markers of a past infection, 12.0% signs of active infection, suggesting that the virus circulates within household members. The high prevalence among siblings (23.6%) demonstrates the importance of personal contact in the transmission of this virus. Another indirect indicator of intra-familial transmission was the high prevalence of HBV markers within contacts of a fulminant hepatitis. The vertical transmission of HBV in our region may or may not occur, but if it does it as a rare event. Our results demonstrate the importance of the presence of HBV, and demand other investigations to clarify the inter-familial transmission of these viruses in our region.

Prevalência de marcadores para o vírus da hepatite B em contatos domiciliares no Estado do Amazonas / Prevalence of hepatitis B virus markers within household contacts in the state of Amazonas

O objetivo do estudo foi analisar o comportamento intrafamiliar da infecçäo pelo VHB, identificando os possíveis mecanismos de transmissäo dos vírus B no Estado do Amazonas. Foram estudados 97 casos índices e 258 familiares. Na análise dos contatos observou-se uma elevada proporçäo de familiares com marcadores de infecçäo pregressa (51,6 por cento) como também indicadores de infecçäo ativa (12 por cento) para o VHB, e uma alta prevalência entre os irmäos (23,6 por cento). Um indicador indireto da transmissäo intrafamiliar foi observado em razäo de elevada freqüência de infecçäo pelo VHB entre os contatos de casos índices acometidos pela forma fulminante de hepatite. A alta prevalência entre os irmäos caracteriza a transmissäo de caráter horizontal e familiar. Em relaçäo a transmissäo vertical, em nosso estado, é possível que ocorra, mas, como um evento raro. Todas estas observaçöes apontam para a necessidade de novas investigaçöes visando o esclarecimento dos mecanismos pelos quais se dá a transmissäo intrafamiliar desse agente viral