title: Occult hepatitis B virus infection in hemodialysis patients in Recife, State of Pernambuco, Brazil.
abstract: BACKGROUND
  Persistence of the hepatitis B virus (HBV) genome in individuals negative for the HBV surface antigen (HBsAg) reflects occult infection. The aim of this study was to identify occult HBV infection among hemodialysis patients at 5 clinics in Recife, State of Pernambuco, Brazil, between August 2006 and August 2007.
  
  
  METHODS
  Serum samples underwent enzyme-linked immunosorbent assay to investigate total antibodies against HBcAg (anti-HBc), HBsAg, and antibodies against HBsAg (anti-HBs). Samples that were HBsAg-negative were tested for total anti-HBc, and those that were positive for total anti-HBc were tested for anti-HBs. HBV DNA was investigated with an in-house PCR technique to identify samples positive for total anti-HBc. Subsequently, the samples positive for HBV DNA were sequenced to identify the genotype and mutations.
  
  
  RESULTS
  The study population (n = 752) had a mean age of 50 15.1 years and included both sexes. All samples analyzed were negative for HBsAg. The seroprevalence of total anti-HBc was 26.7% (201/752), while that of anti-HBs was 67.2% (135/201). Total anti-HBc alone was detected in 5.7% of the patients. Occult infection was found in 1.5%, comprising genotypes A (33.3%, 1/3) and D (66.7%, 2/3). No mutations were found.
  
  
  CONCLUSIONS
  The study detected occult hepatitis B virus infection in hemodialysis patients. Molecular studies on HBV are of fundamental importance because they identify patients that had been considered virus-negative but who, in reality, host the virus and have the ability to transmit it to other patients and staff.
authors.affiliation: Bairro Universitário, Caruaru, PE, Brasil. anaceciliaprofa@yahoo.com.br
authors.forename: Ana Cecília Cavalcanti de
authors.initials: AC
authors.lastname: Albuquerque
authors.forename: Maria Rosângela Cunha Duarte
authors.initials: MR
authors.lastname: Coelho
authors.forename: Marcílio Figueiredo
authors.initials: MF
authors.lastname: Lemos
authors.forename: Regina Célia
authors.initials: RC
authors.lastname: Moreira
mesh_terms: D000328:Adult; D000368:Aged; D001938:Brazil / Q000453:epidemiology; D003430:Cross-Sectional Studies; D004279:DNA, Viral / Q000097:blood*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005838:Genotype; D006509:Hepatitis B / Q000175:diagnosis / Q000453:epidemiology*; D006510:Hepatitis B Antibodies / Q000097:blood*; D006514:Hepatitis B Surface Antigens / Q000097:blood*; D006515:Hepatitis B virus / Q000235:genetics / Q000276:immunology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009154:Mutation; D016133:Polymerase Chain Reaction; D015995:Prevalence; D006435:Renal Dialysis / Q000009:adverse effects*
chemical_list: D004279:DNA, Viral; D006510:Hepatitis B Antibodies; D006514:Hepatitis B Surface Antigens