Molecular evidence of nosocomial transmission of hepatitis C virus in a haemodialysis unit

The molecular epidemiology of type 2a hepatitis C virus (HCV) infections in patients undergoing haemodialysis in the same unit in a Turkish hospital was investigated. Of nine HCV-infected patients four were infected with type 2a, four with type Ib and one with type la viruses. Since type 2 HCV infections in the Turkish population are rare, the possibility of nosocomial infection was investigated by means of phylogenetic analysis of viral sequences amplified by the polymerase chain reaction in the NS5b region. One of the samples failed to show amplification and therefore could not be sequenced. The sequences of the remaining three virus samples were grouped closely in a cluster within the type 2a group. The results thus showed that three patients were infected with the same HCV type 2a strain. Seroconversion and clinical data suggested that these patients may have been infected on different occasions, there being possibly more than one mode of transmission. Breaches in infection control procedures and lack of environmental decontamination between two haemodialysis sessions were probably the causes of HCV infections in these patients.