Worldwide, between 123 and 170 million people are chronically infected with the hepatitis C virus (HCV) [1
]. Injection drug users (IDUs) constitute the largest group of persons infected with HCV and those most afflicted by new infections in developed countries [2
]. Prevalence and incidence rates for HCV infection in general IDU populations (different rates in younger or older IDUs) are as high as 91% and 45.8 per 100 person-years, respectively [4
]. There is evidence that many IDUs become infected with HCV early in their injecting career [6
] and that the highest rates of HCV infection are observed among those who report a history of sharing drug preparation or injection equipment [3
While the sharing of contaminated syringes is regarded as a major contributor to HCV infection, syringes may be only one source of injection-related infection. Drug mixing containers, cotton filters and rinse water, have garnered support in recent years as additional sources of bloodborne infection [9
]. Opportunities for viral transmission through drug preparation equipment may exist at various stages of the injection process. For example, water used to prepare a drug solution can become contaminated with HCV if the solution is mixed with a syringe previously used for injection. Clean syringes can become contaminated when a drug solution is drawn from a container or through a filter previously used by an HCV-infected injector. Cleaning a syringe, container or filter with contaminated rinse water may also lead to viral cross-contamination of drug preparation and injection equipment.
There remains continuing debate about the relative contribution of syringes compared with drug preparation equipment in relation to HCV transmission [11
]. Biologically, needles and syringes have the greatest potential for carrying HCV because of their direct contact with blood during venipuncture. However, the persistence of the hepatitis C virus in used drug preparation equipment is supported by laboratory evidence which shows that between 25% and 40% of filters, spoons and rinse water samples may harbour HCV RNA [13
]. While the epidemiologic evidence for the association between HCV infection and drug preparation equipment sharing is not well established, support for ancillary injection materials is mounting as additional studies are carried out. A recent simulation study found that the probability of HCV infection was higher for syringes compared with other equipment during the first 5 years of injecting but was similar after 25 years [14
]. Consequently, the authors of the study suggested that there may be more rapid spread of HCV through syringes during the initial years of injecting after which continued exposure to contaminated drug preparation equipment can lead to an elevated risk of HCV seroconversion.
To our knowledge, a review of the risk of HCV infection associated with drug preparation equipment has not yet been published in the medical literature. Therefore, the objective of this review was to critically appraise the evidence regarding HCV transmission risk from shared drug preparation equipment and to comment on whether the risk of HCV infection differs according to the type of drug preparation equipment shared.