Phylogenetic evidence, by multiple clone analysis of hypervariable region 1, for the transmission of hepatitis C virus to chronic haemodialysis patients

We analysed hepatitis C virus (HCV) sequences to determine whether nosocomi al transmission of HCV occurred in a haemodialysis unit. Twenty patients po sitive for serum HCV RNA were investigated. All were undergoing haemodialys is therapy in the same room. The hypervariable region 1 (HVR1) sequence of HCV was amplified and multiple clones sequenced. Phylogenetic analysis of t hese sequences revealed five genetic clusters consisting of HCV isolates fr om 11 of the 20 patients. In addition to two genetic clusters of HCV isolat es from the four currently seroconverting patients and another patient who had been persistently infected, we identified three other phylogenetic rela tionships in HCV isolates from six patients. The patients grouped into the same cluster received haemodialysis individually on the same shift and/or s ide-by-side. Phylogenetic analysis of HCV HVR1 sequences corroborated the p atient-to-patient HCV transmission suggested by an epidemiological study an d that unrecognized transmission of HCV occurs in the dialysis room. Our mu ltiple clone analysis of HCV isolates provides detailed information on noso comial transmission of HCV. Transmission occurs more frequently when treatm ent is performed at the same time than in consoles located close to each ot her.