Analysis of HBV infection after blood transfusion in Japan through investigation of a comprehensive donor specimen repository

BACKGROUND: To understand the risk of transfusion-transmitted viral infecti on, it is important to precisely assess cases of infection that follow tran sfusion. STUDY DESIGN AND METHODS: HBV infections noted after transfusion in 1997, 1 998, and 1999 were analyzed. Transfusion in all these cases was performed b efore NAT was adopted for donor screening. To detect viral infection, PCR a nd serologic tests for HBV were performed retrospectively on all blood samp les from implicated donors that had been stored in a frozen state after eac h donation. The concentration of HBV genome was measured in HBV-positive bl ood samples. RESULTS: One hundred three cases of HBV infection were analyzed; of these, only 16, including at least 10 infections due to window-period (HBsAg-posit ive by reverse particle hemagglutination assay) donations, were confirmed b y further testing to be related to transfusion. The concentrations of HBV g enome were very low in four blood samples (< 50, 400, 500, and 800 genome e quivalents/mL of plasma). CONCLUSIONS: The remaining risk of transfusion transmission of HBV infectio n before the adoption of NAT was mainly due to window-period donations, inc luding one that was made before the HBV genome was detectable by PCR. Howev er, it was determined that transfusion was not responsible in many cases fo r HBV infection after transfusion.