title: Poor efficacy of nucleic acid testing in identifying occult HBV infection and consequences for safety of blood supply in Italy.
abstract: OBJECTIVE
  In Italy, DNA screening of blood donations for hepatitis B virus (HBV) was introduced to prevent the transmission of window period and occult HBV infection. Anti-HBc screening is not recommended in order to avoid shortage of the blood supply. To contain costs, donor samples are generally pooled before testing. We evaluated the safety of this national policy using a prospective repository of donors/recipient pairs.
  
  
  METHODS
  We used highly sensitive nucleic acid testing (NAT) assays to test repository and follow-up samples from donors who were initially classified as negative by minipool NAT assays (6-MP), but were later found to carry occult HBV DNA. When available, we also analysed recipients' pre- and post-transfusion samples, collected in the context of a repository financed by the European Commission (the BOTIA project).
  
  
  RESULTS
  Between 2008 and 2011 6-MP NAT assays identified 18 carriers of occult HBV infection among 12,695 donors; 28 samples from previous donations were available from 13 of these carriers. Highly sensitive HBV DNA detection methods showed that 6-MP HBV DNA screening failed to identify 14/28 (50%) viraemic donations, that were released for transfusion. HBV marker testing of such blood product recipients revealed two cases of transfusion transmitted HBV infection, documented by donor-recipient sequence identity.
  
  
  CONCLUSIONS
  Viraemic blood donations from occult HBV infection carriers remain undetected by current minipool HBV DNA screening, and transfusion transmission of HBV continues to occur in susceptible patients. More effective individual HBV DNA screening and/or tests for antibodies to HBV core antigen should be considered to improve blood safety.
authors.affiliation: Department of Transfusion Medicine and Hematology, Azienda Ospedaliera della Provincia di Lecco, Alessandro Manzoni Hospital, Lecco, Italy. Electronic address: ma.spreafico@ospedale.lecco.it.
authors.forename: Marta
authors.initials: M
authors.lastname: Spreafico
authors.affiliation: Department of Transfusion Medicine and Hematology, Azienda Ospedaliera della Provincia di Lecco, Alessandro Manzoni Hospital, Lecco, Italy.
authors.forename: Alessandra
authors.initials: A
authors.lastname: Berzuini
authors.affiliation: Department of Transfusion Medicine and Hematology, Azienda Ospedaliera della Provincia di Lecco, Alessandro Manzoni Hospital, Lecco, Italy.
authors.forename: Barbara
authors.initials: B
authors.lastname: Foglieni
authors.affiliation: Institut National de la Transfusion Sanguine (INTS), Département d'études des agents transmissibles, F-75015 Paris, France.
authors.forename: Daniel
authors.initials: D
authors.lastname: Candotti
authors.affiliation: Department of Transfusion Medicine and Hematology, Azienda Ospedaliera della Provincia di Lecco, Alessandro Manzoni Hospital, Lecco, Italy.
authors.forename: Livia
authors.initials: L
authors.lastname: Raffaele
authors.affiliation: Department of Transfusion Medicine and Hematology, Azienda Ospedaliera della Provincia di Lecco, Alessandro Manzoni Hospital, Lecco, Italy.
authors.forename: Irene
authors.initials: I
authors.lastname: Guarnori
authors.affiliation: Department of General Medicine, Azienda Ospedaliera della Provincia di Lecco, Alessandro Manzoni Hospital, Lecco, Italy.
authors.forename: Agostino
authors.initials: A
authors.lastname: Colli
authors.affiliation: Department of Transfusion Medicine and Hematology, Azienda Ospedaliera della Provincia di Lecco, Alessandro Manzoni Hospital, Lecco, Italy.
authors.forename: Francesco Fumagalli
authors.initials: FF
authors.lastname: Maldini
authors.affiliation: Department of Haematology, University of Cambridge, Cambridge, UK.
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Allain
authors.affiliation: Department of Transfusion Medicine and Hematology, Azienda Ospedaliera della Provincia di Lecco, Alessandro Manzoni Hospital, Lecco, Italy. Electronic address: d.prati@ospedale.lecco.it.
authors.forename: Daniele
authors.initials: D
authors.lastname: Prati
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000465:Algorithms; D001782:Blood Donors; D004279:DNA, Viral / Q000032:analysis*; D005260:Female; D006509:Hepatitis B / Q000175:diagnosis* / Q000453:epidemiology / Q000635:transmission; D006515:Hepatitis B virus / Q000235:genetics*; D006801:Humans; D015994:Incidence; D007558:Italy / Q000453:epidemiology; D008297:Male; D008403:Mass Screening / Q000379:methods*; D008875:Middle Aged; D021141:Nucleic Acid Amplification Techniques / Q000379:methods*; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012189:Retrospective Studies; D055815:Young Adult
chemical_list: D004279:DNA, Viral
keywords: Nucleic acid technology; Occult HBV infection; Transfusion transmitted HBV