TRANSMISSION OF THE HEPATITIS-C VIRUS IN AN HEMODIALYSIS UNIT - EVIDENCE FOR NOSOCOMIAL INFECTION

Hepatitis C virus (HCV) infection is a frequent feature in hemodialysi s (HD) patients. The way of viral transmission is difficult to establi sh, but in previous studies the role of blood transfusions and of HD t reatment duration, and the possibility of nosocomial transmission of t he virus have been suggested. We present here the results of a virolog ical follow-up of HCV infection in our HD unit in 1993-1994, and a mol ecular study of viral strains that led to a possible reconstruction of viral spreading. All patients in our unit were regularly tested for a lanine aminotransferase, HCV antibodies and HCV RNA in serum. Seven se roconversions were detected during follow-up, and a high proportion of type 1b HCV strains was found in infected patients. Nucleotide sequen ces located in the envelope 1 (E1) viral coding region of type 1b stra ins were compared in our patients and numerous controls infected with the same HCV genotype. A high proportion of patients with antibodies t o HCV were detected in our unit (32.5%). Blood transfusions and durati on of HD treatment were risk factors for HCV infection. Seroconversion s in patients never transfused and predominance of type 1b HCV strains suggested that infection had occurred via the nosocomial pathway in o ur unit. Similar sequences in the E1 region were found in four patient s treated, forming a distinct cluster in a phylogenetic tree. Of these four patients, two had been infected before 1991, and the others made a seroconversion for HCV at the same period in 1994. In all other pat ients, including a nurse who had been in charge of some infected patie nts, distinct strains were found. Duration of HD treatment seems to be a major factor of risk for HCF infection in HD units. Contamination c ould occur during blood transfusion or via the nosocomial pathway thro ugh a crossinfection mechanism from patients already infected. The lat ter mechanism was formally demonstrated in this study.