Hepatitis C seroprevalence amongst injecting drug users attending a methadone programme

To study the seroprevalence of the hepatitis C virus (HCV) amongst a population of injecting drug users and to examine the relationship between potential risk factors and HCV infection.

A sample of 116 clients attending a methadone treatment clinic in Christchurch took part in this study. Blood samples were analysed to detect antibodies to HCV and to test for HCV RNA: Serum transaminases were also measured. In addition a short questionnaire about sexual behaviour and drug use practices was self completed by all participants in strictest confidence.

Slightly more than half the sample were female (54.3%) and most were of European origin (90.6%). The average age was 31.56 years and the average length of time they had been injecting drugs was 9.54 years. HCV antibodies were detected in 84.2% of the sample and HCV RNA in 66.1% of the sample including 75.9% amongst those who were anti-HCV positive and 16.6% amongst those who were anti-HCV negative. AST and ALT levels were elevated amongst 16.8% and 46.2% of the sample respectively. The likelihood of being anti-HCV positive increased with years of drug use and with increased sharing of injecting equipment. No significant relationship between HCV status and sexual practices was evident. Data on the history of drug using practices indicated that sharing of injecting equipment had become less common over time and access to new equipment through reliable sources had become more common with time.

HCV is widespread amongst this population of injecting drug users suggesting the possibility of a major clinical and social problem. Despite evidence of a reduction in the sharing of injecting equipment, HCV transmission is still occurring indicating the potential for other parenterally transmitted diseases, such as HIV, to become established amongst injecting drug users. Those at high risk of HCV should be discouraged from donating blood because of the possibility of HCV seronegative infectivity.