Italian blood donors with anti-HBc and occult hepatitis B virus infection.
OBJECTIVE
Occult hepatitis B virus (HBV) infection might allow the release of viremic units into the blood supply network if blood is tested only for hepatitis B surface antigen (HBsAg). The aim of our study was to evaluate the actual prevalence, viral load and genotype of occult HBV infections among first-time blood donors in north-western Italy and to suggest a way to minimize risks of transmission of this infection.


METHODS
We assayed 6313 consecutive blood donors for antibodies to HBV core antigen (anti-HBc) in addition to mandatory screening. HBsAg-negative/anti-HBc-positive donors were assayed for antibodies to HBsAg (anti-HBs) and for HBV-DNA using COBAS Ampliscreen HBV (Roche) on individual donations. All HBV-DNA-positive samples underwent confirmatory testing with additional polymerase chain reaction-based assays.


RESULTS
The prevalence of anti-HBc positive subjects was 4.85%. Fourteen out of 288 blood donors (4.86%) were confirmed to have circulating HBV-DNA at a low level (range 8-108 IU/mL). All viremic donors were also anti-HBs-positive.


CONCLUSIONS
We estimate that in north-western Italy up to 2298 units per million donated units from first-time donors may contain HBV-DNA. The risk of an HBV-DNA positive unit from an occult carrier being released into the blood supply is more than 100 times higher than the estimated residual risk related to the window phase of HBV infection in our country. The potential infectivity of these units is debated, but their use cannot be considered safe at least in immunocompromised patients.
Banca del Sangue e del Plasma, A.O. S. Giovanni Battista di Torino, Corso Bramante 88, 10126 Torino, Italy. pmanzini@molinette.piemonte.it
Paola
P
Manzini
Mauro
M
Girotto
Raffaele
R
Borsotti
Osvaldo
O
Giachino
Roberto
R
Guaschino
Maurizio
M
Lanteri
Domenico
D
Testa
Paola
P
Ghiazza
Maria
M
Vacchini
Franca
F
Danielle
Alessandra
A
Pizzi
Chiara
C
Valpreda
Franco
F
Castagno
Franco
F
Curti
Paola
P
Magistroni
Maria Lorena
ML
Abate
Antonina
A
Smedile
Mario
M
Rizzetto
D001782:Blood Donors; D015331:Cohort Studies; D004279:DNA, Viral / Q000097:blood* / Q000235:genetics; D046148:Donor Selection; D005260:Female; D006509:Hepatitis B / Q000097:blood* / Q000453:epidemiology* / Q000235:genetics / Q000276:immunology / Q000517:prevention & control; D006510:Hepatitis B Antibodies / Q000097:blood* / Q000276:immunology; D006512:Hepatitis B Core Antigens / Q000276:immunology; D006515:Hepatitis B virus / Q000235:genetics / Q000276:immunology; D006801:Humans; D007558:Italy; D008297:Male; D016133:Polymerase Chain Reaction; D015995:Prevalence
D004279:DNA, Viral; D006510:Hepatitis B Antibodies; D006512:Hepatitis B Core Antigens