Unsafe injecting results in increased rates of hepatitis C and HIV among populations of injecting drug users. It is well established that it is unsafe to use needles or syringes that have previously been used by another injecting drug user. There is growing evidence that it is unsafe to share a "cooker", filter, or other injecting paraphernalia with another injector. Most injecting drug users in Dublin report sharing of syringes and injecting paraphernalia. In Dublin, the prevalences of HIV and hepatitis C among injecting drug users were found to be 1.2% and 61.8% respectively.

The incidence of hepatitis C among injecting drug users has now been examined in North America, Australia, and a number of European countries and has ranged from 16 to 38 per 100 person years. We sought to measure the incidence of hepatitis C and HIV among injecting drug users in Dublin.