title: Prevalence of hepatitis A virus infection: the paradoxical example of isolated communities in the western Brazilian Amazon region.
abstract: This study evaluated the prevalence of hepatitis A virus infection in the rural area of Lábrea, in the western Brazilian Amazon region. Communities and households were selected randomly. Serum samples were analyzed by means of the immunoenzymatic method for the presence of total antibodies against HAV. The study included 1,499 individuals. The prevalence of anti-HAV was 74.6% (95% CI 72.3-76.8). Univariate analysis showed associations with age (chi-square for linear trend = 496.003, p < 0.001), presence of outside toilet (p < 0.001), history of hepatitis (p < 0.001) and family history of hepatitis (p = 0.05). After adjusting for age, HAV infection also showed an association with the number of people in the family (p = 0.03). The overall prevalence rates were high, but not more than 60% of the children under the age of ten years had already been infected. Very high prevalence was detected only within older cohorts, thus paradoxically defining this as a region with intermediate endemicity, even under the conditions of poverty encountered.
authors.affiliation: Virology Unit, Tropical Medicine Foundation of Amazonas, Av. Pedro Teixeira 25, Manaus, AM, Brazil. wornei.braga@hotmail.com
authors.forename: Wornei Silva Miranda
authors.initials: WS
authors.lastname: Braga
authors.forename: Fabiane Giovanella
authors.initials: FG
authors.lastname: Borges
authors.forename: Gildo Maia
authors.initials: GM
authors.lastname: Barros Júnior
authors.forename: Ana Cristina de Souza
authors.initials: AC
authors.lastname: Martinho
authors.forename: Ivo Seixas
authors.initials: IS
authors.lastname: Rodrigues
authors.forename: Eliete Pereira de
authors.initials: EP
authors.lastname: Azevedo
authors.forename: Gustavo Henrique Nolasco Grimmer
authors.initials: GH
authors.lastname: Davis
authors.forename: Manoel Bezerra de
authors.initials: MB
authors.lastname: Queiroz
authors.forename: Simone Helena Derzi dos
authors.initials: SH
authors.lastname: Santos
authors.forename: Thiago Vitoriano
authors.initials: TV
authors.lastname: Barbosa
authors.forename: Márcia da Costa
authors.initials: Mda C
authors.lastname: Castilho
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001938:Brazil / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D005260:Female; D006506:Hepatitis A / Q000175:diagnosis / Q000453:epidemiology*; D035922:Hepatitis A Antibodies / Q000097:blood*; D030041:Hepatitis A virus / Q000276:immunology*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D012424:Rural Population; D016036:Seroepidemiologic Studies; D055815:Young Adult
chemical_list: D035922:Hepatitis A Antibodies