title: Prevalence of occult hepatitis B infection in a highly endemic area for chronic hepatitis B: a study of a large blood donor population.
abstract: OBJECTIVE
  The aim of the present study was to determine the population prevalence of occult hepatitis B (OHB) infection and its clinical profile in a highly endemic area of chronic hepatitis B virus disease.
  
  
  METHODS
  OHB was first identified by individual sample testing for hepatitis B surface antigen (HBsAg) followed by nucleic acid testing (NAT) and vice versa for 3044 (cohort 1, stored sera from donation within 1 year) and 9990 (cohort 2, prospective study) blood donors, respectively. OHB was confirmed meticulously by ≥2 out of 3 tests with detectable hepatitis B virus (HBV) DNA using a sensitive standardised assay. Detailed serology and viral load in the serum and liver were studied.
  
  
  RESULTS
  The prevalence of OHB was 0.13% (4/3044) and 0.11% (11/9967) for cohort 1 and 2, respectively. In cohort 2, 10 out of 11 OHB samples were positive for anti-HBc (hepatitis B core antigen) antibody (all were immunoglobulin G). Seven had detectable anti-HBs. The serum HBV DNA levels were extremely low (highest 14.1 IU/ml). Of the six donors who underwent liver biopsies, all had normal liver biochemistry, extremely low liver HBV DNA (highest 6.21 copies/cell) and nearly normal liver histology. For those with viral sequence generation, none had the common HBsAg mutant G145R.
  
  
  CONCLUSIONS
  The prevalence of OHB in a highly endemic area of chronic HBV was very low, thus implying a low impact on transfusion services. To implement universal screening, the high cost of NAT should be taken into account. OHB blood donors had very low HBV replication, and normal liver biochemistry and histology, conferring a favourable prognosis.
authors.affiliation: Department of Medicine, The University of Hong Kong, Queen Mary Hospital, Pokfulam Road, Hong Kong.
authors.forename: Man-Fung
authors.initials: MF
authors.lastname: Yuen
authors.forename: Cheuk-Kwong
authors.initials: CK
authors.lastname: Lee
authors.forename: Danny Ka-Ho
authors.initials: DK
authors.lastname: Wong
authors.forename: James
authors.initials: J
authors.lastname: Fung
authors.forename: Ivan
authors.initials: I
authors.lastname: Hung
authors.forename: Axel
authors.initials: A
authors.lastname: Hsu
authors.forename: David Yiu-Kuen
authors.initials: DY
authors.lastname: But
authors.forename: Ting-Kin
authors.initials: TK
authors.lastname: Cheung
authors.forename: Pierre
authors.initials: P
authors.lastname: Chan
authors.forename: John Chi-Hang
authors.initials: JC
authors.lastname: Yuen
authors.forename: Frederic Khe-Cheong
authors.initials: FK
authors.lastname: Fung
authors.forename: Wai-Kay
authors.initials: WK
authors.lastname: Seto
authors.forename: Che-Kit
authors.initials: CK
authors.lastname: Lin
authors.forename: Ching-Lung
authors.initials: CL
authors.lastname: Lai
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001782:Blood Donors / Q000706:statistics & numerical data*; D001803:Blood Transfusion; D002353:Carrier State / Q000453:epidemiology* / Q000473:pathology; D015331:Cohort Studies; D004279:DNA, Viral / Q000032:analysis; D019353:Endemic Diseases; D005260:Female; D006514:Hepatitis B Surface Antigens / Q000097:blood; D006515:Hepatitis B virus / Q000302:isolation & purification; D019694:Hepatitis B, Chronic / Q000453:epidemiology* / Q000473:pathology; D006723:Hong Kong / Q000453:epidemiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D055815:Young Adult
chemical_list: D004279:DNA, Viral; D006514:Hepatitis B Surface Antigens