Occult hepatitis B virus infection among blood donors from the Brazilian Amazon: implications for transfusion policy.
BACKGROUND
Brazil requires the performance of both a test for hepatitis B surface antigen (HBsAg) and a test for antibodies to the core of hepatitis B for blood donor screening. Blood centres in regions of high HBV endemicity struggle to maintain adequate stocks in face of the high discard rates due to anti-HBc reactivity. We evaluated the potential infectivity of donations positive for anti-HBc in search of a rational approach for the handling of these collections.


METHODS
We tested anti-HBc reactive blood donations from the state of Amazonas for the presence of HBV DNA and for titres of anti-HBs. The study population consists of village-based donors from the interior of Amazonas state.


RESULTS
Among 3600 donations, 799 were anti-HBc reactive (22·2%). We were able to perform real-time PCR for the HBV S gene on specimens from 291 of these donors. Eight of these samples were negative for HBsAg and positive for HBV DNA and were defined as occult B virus infections (2·7%). Six of those eight specimens had anti-HBs titres above 100 mIU/ml, indicating the concomitant presence of the virus with high antibody titres.


CONCLUSIONS
A small proportion of anti-HBc reactive donors carry HBV DNA and anti-HBs testing is not useful for predicting viremia on them. This finding indicates the possibility of HBV transmission from asymptomatic donors, especially in areas of high HBV prevalence. Sensitive HBV DNA nucleic acid testing may provide another level of safety, allowing eventual use of anti-HBc reactive units in critical situations.
Programa de Pós-Graduação em Imunologia Básica e Aplicada da, Universidade Federal do Amazonas, Manaus, Amazonas, Brazil.
M N dos S
MN
Moresco
H de A
Hde A
Virgolino
M P E
MP
de Morais
I
I
da Motta-Passos
M S
MS
Gomes-Gouvêa
L M S
LM
de Assis
K R de L
KR
Aguiar
S C F
SC
Lombardi
A
A
Malheiro
N de P
Nde P
Cavalheiro
J E
JE
Levi
K L
KL
Torres
D000328:Adult; D001782:Blood Donors; D001803:Blood Transfusion / Q000379:methods* / Q000592:standards; D001938:Brazil / Q000453:epidemiology; D003140:Communicable Disease Control / Q000379:methods*; D004279:DNA, Viral / Q000097:blood / Q000302:isolation & purification; D006509:Hepatitis B / Q000097:blood* / Q000453:epidemiology*; D006510:Hepatitis B Antibodies / Q000097:blood; D006512:Hepatitis B Core Antigens / Q000276:immunology; D006514:Hepatitis B Surface Antigens / Q000097:blood; D006515:Hepatitis B virus / Q000235:genetics; D006801:Humans; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D060888:Real-Time Polymerase Chain Reaction; D014766:Viremia / Q000097:blood
D004279:DNA, Viral; D006510:Hepatitis B Antibodies; D006512:Hepatitis B Core Antigens; D006514:Hepatitis B Surface Antigens
Brazilian Amazon; HBV DNA; blood donors; occult hepatitis B