Occult Hbv Infection in Hbsag Negative and Anti-Hbc Positive Blood Donors.

In recent years with introduction of better screening tests, the risk of infection with transfusion-transmitted viruses has been reduced remarkably, although obtaining a zero-risk blood supply still remains international blood transfusion services goal. The routine test for detection of HBV infected blood samples is examination of HBsAg with ELISA method but in occult HBV infection, HBsAg is not detectable by ELISA. Therefore, a more sensitive or complementary test is needed. Some international blood transfusion services have introduced anti-HBc screening as a surrogate test for the presence of HBV infection. The aim of this study was to evaluate the prevalence of occult HBV infection in Isfahanian blood donors and the potential value of anti-HBc testing of donors as a screening test to detect occult HBV infection.

In this descriptive cross-sectional study, 545 blood units were collected (from Isfahan blood center) and tested by HBsAg ELISA kit from April to June 2004 and then all HBsAg negative samples were tested by anti-HBc ELISA kit. To detect occult HBV infection, all HBsAg negative and anti-HBc positive samples were tested by PCR method.

All samples were negative for HBsAg while 43 blood units were anti-HBc positive (8%). These HBsAg negative and anti-HBc positive blood units were tested for HBV DNA of which five units (%11.6) were HBV DNA positive.

Occult HBV infection is a clinical form of HBV infection that cannot be detected by usual method (ELISA) for HBsAg and therefore more sensitive techniques are needed for detection of HBV infection. PCR is a sensitive technique that detects HBV DNA even in a trace mounts. Our results identified that more sensitive and complementary tests such as, PCR and anti-HBc, are essential and helpful to ensure safety of blood units.