Molecular analysis and patterns of ALT and hepatitis C virus seroconversion in haemodialysis patients with acute hepatitis.

Background: Haemodialysis (HD) continues to carry the risk of hepatitis C virus (HCV) transmission, with delayed seroconversion and often normal alanine aminotransferase (ALT) values increasing the likelihood of undetected infection and thus uninterrupted spread of HCV. The aim of this study was to identify the characteristic patterns of ALT changes and seroconversion during an outbreak of HCV in a HD unit. We also wanted to establish the relationship between infecting viruses using molecular analysis. Methods: All patients (n = 72) and staff (n = 23) of the HD unit were prospectively followed for 14 months. Serial measurements for ALT, HCV antibody and HCV-RNA were performed besides HCV sequence analysis. Results: The initial screening for anti-HCV and HCV-RNA confirmed chronic infection in 16/72 (22%) subjects and identified three subjects with recent seroconversion. In addition, five cases were reverse transcription-polymerase chain reaction positive alone for a total of eight recent cases. The interval between the initial observation of ALT changes and seroconversion varied from 1 to 8 months, and in several individuals ALT fluctuations only below the upper limit of normal were detected. However, relating each subject's ALT values to ALT at baseline, ALT levels increased between 1.6- and 4.7-fold. Molecular analysis provided evidence for transmission from two chronically infected source patients, probably because of inappropriate infection control measures. Conclusion: Our data highlight the importance of well-implemented safety precautions and regular HCV-RNA testing to prevent the further spread of HCV in this population, and suggest the use of ALT baseline values to identify infections that may remain unnoticed otherwise.