An unusual strain of hepatitis C virus in New Zealand.

AIMS: To investigate the prevalence of hepatitis C virus (HCV) viraemia in selected cohorts of New Zealand patients and to examine the strains of hepatitis C virus circulating in New Zealand. METHODS: Hepatitis C viraemia was identified using a highly sensitive polymerase chain reaction (PCR) assay to detect HCV ribonucleic acid (RNA). Selected virus isolates were analysed for strain variation by restriction fragment length polymorphism (RFLP) of PCR products and two of the amplified products were sequenced. RESULTS: A high frequency of HCV viraemia was found in patients with a history of repeated exposures to blood or blood products. RFLP analysis revealed the prevalence of an unusual strain of hepatitis C which was further confirmed by sequencing. Identification of the infecting hepatitis C strains resolved a suspected point source outbreak occurring in a maximum security prison. CONCLUSIONS: Detection of circulating hepatitis C RNA is a sensitive and specific method for identifying active hepatitis C infection. Typing hepatitis C isolates has useful epidemiological application and facilitates the detection of unusual HCV variants.