Low rate of occult hepatitis B virus infection among anti-HBc positive blood donors living in a low prevalence region in Brazil

Objective. The aim of this study was to determine the rate of occult hepatitis B virus (HBV) infection among blood donors living in a geographic region of low (5.6%) anti-HBc prevalence. Subjects and methods. Sera from 150 candidate blood donors whose blood was rejected due to total anti-HBc reactivity (despite absence of HBsAg) were tested for anti-HBs and IgM anti-HBc antibodies, as well as for HBeAg/anti-HBe. Serum HBV DNA was sought by using a PCR assay able to amplify part of the surface gene. Viral toad was measured in the PCR positive samples. Results. The pattern 'anti-HBc atone' (without HBsAg and anti-HBs antibodies) was found in 64 (42.7%) subjects. IgM anti-HBc and anti-H Be antibodies were detected in 2 (1.3%) and 80 (53.3%) samples, respectively. No sample was HBeAg-reactive. HBV DNA was repeatedly found in five (3.3%) samples, three of which were anti-HBs positive and two anti-HBs negative. All five HBV DNA positive samples showed a low viral toad (< 1000 copies/ml). Conclusions. The data indicated a low rate of occult infection among anti-HBc positive, HBsAg negative blood donors living in a region of tow prevalence of infection. Viral load was very tow in all HBV infected subjects. (c) 2004 The British Infection Society. Published by Elsevier Ltd. All rights reserved.