Yield of nat screening in Slovenia

Abstract

Background: Safe blood supply is the main goal of blood transfusion services. Nucleic Acid Amplification Technologies (NAT) are the methods for direct detection of viral genoms in various biological samples. Introduction of NAT blood screening reduces the risk for transfusion transmitted diseases and improves the safety. Methods and Results: In Slovenia NAT screening with PCR (Polymerase Chain Reaction) method for testing pools of samples for hepatitis C virus (HCV) RNA was implemented in 2000. The screening is mandatory for all donations. Until 2007, 590,000 donated units had been screened and there were no HCV RNA-only positive result.In 2007, the testing was expanded to three viruses: HCV, hepatitis B virus (HBV) and human immunodeficiency virus (HIV). The testing method was TMA (Transcription Mediated Amplification) performed on individual donations. In five-year period, 458,000 blood units were screened and two window-period donations positive for HCV were detected (yield 1:524,000). HBV DNA-only was detected in 29 units. All the cases were donors with a resolved HBV infection, in one case the recent one, in others the occult hepatitis B infection (OBI) was confirmed. The yield of NAT testing for HBV is 1:15,600 units. There were no donations with HIV 1 RNA-only result. In all 5 HIV positive units in this period, anti-HIV antibodies were present as well. The yield of HIV NAT-only is thus 0:460,000. Conclusion: The implementation of NAT screening for three viruses has improved the blood safety. In the five-year period, 31 infectious units that were NAT–only positive were eliminated from the stock.