Sharing drug preparation paraphernalia may not significantly contribute to hepatitis C virus (HCV) transmission among people who inject drugs, according to a study recently published in The Journal of Infectious Diseases.
In an experiment designed to mimic real-world injection practices, the researchers were unable to detect HCV in cookers, and seldom able to do so in filters, after these items were exposed to the contents of syringes known to be contaminated with the virus.
Needle exchange and distribution programmes that provide sterile syringes have been credited with substantially reducing transmission of blood-borne diseases including HIV, hepatitis B and hepatitis C among people who inject drugs.
These viruses – especially HCV, which is able to live outside the body longer than HIV – can potentially be transmitted through any item that comes into contact with blood. Most harm reduction programmes therefore offer drug preparation equipment such as cookers (bottle caps or other small receptacles used to mix drugs), filters (cotton or other material used to strain a drug solution) and clean water, in addition to syringes.
Robert Heimer of Yale University School of Public Health and colleagues conducted a study to look for HCV in drug preparation paraphernalia under conditions similar to those that occur when people share drugs.
Previous studies by Heimer and others have suggested that cookers and filters can transmit HCV. However, it is unclear if HCV infections linked to sharing paraphernalia reflect contamination of the paraphernalia itself, or if the virus spreads through syringes when drugs are shared, the authors noted as background.
The researchers designed laboratory experiments to replicate real-world injection practices among people who share drugs. Often people will jointly obtain a bag of heroin, for example, which one individual mixes in his or her syringe, and the solution is then portioned out to the others. Older and more experienced users – who have had more opportunities to acquire HCV – may be more likely to do this drug preparation.
The residual contents of ‘input’ syringes known to be contaminated with HCV were passed through cookers and filters and transferred into a second ‘receptive’ syringe. The study tested syringes with detachable needles and those with fixed needles (e.g. disposable insulin syringes). All items were then tested for the presence of infectious HCV.
HCV could not be recovered from cookers, regardless of cooker design or the type of syringe used, according to the report. The virus was only detected in input syringes with detachable needles, not those with fixed needles (73.8 vs 0% detection).
HCV was seldom found in filters, but this happened more often when detachable needles were used compared with fixed needles (15.4 vs 1.4% detection). Finally, HCV was about twice as likely to be detected in the receptive syringe if the input syringe had a detachable instead of a fixed needle (93.8 vs 45.7% detection).
These results are "consistent with the hypothesis that sharing paraphernalia does not directly result in HCV transmission, but is a surrogate for transmissions resulting from sharing drugs," the study authors concluded. They suggested that this kind of sharing "is a surrogate for situations in which HCV-discordant injectors share drugs," meaning one individual is HCV-positive and the other HCV-negative.
The findings, they added, have implications for HCV prevention efforts and programmes that provide education and safe injection supplies for people who inject drugs.
Heimer's team suggested that in light of these results, syringe access programmes should not spend their limited funds on cookers and filters, but should instead focus their efforts on distributing more syringes with fixed needles.
"At a minimum, our findings should compel programs that serve [people who inject drugs] to focus more on the process of drug preparation and injection and less on the preparation paraphernalia," they wrote. "Going further, programs may want to reconsider expending scarce resources to provide supplies that will do little or nothing to prevent HCV transmission."
Some harm reduction advocates, however, take issue with this conclusion. Beyond HCV transmission, providing clean cookers and filters can also help prevent bacterial infections and 'cotton fever'. And these supplies are inexpensive, so omitting them would not free up much money.
"We are in the midst of a syringe exchange funding crisis, as a surge in demand (more people who inject drugs) plus a tremendous growth in new programs has dramatically outpaced availability of public and private funds," said Daniel Raymond of the Harm Reduction Coalition. "However, any discussions or decisions about scaling back on purchasing or provision of cookers, etc, should be driven by people who inject drugs and program participants, who may place values on these supplies independent of their utility in HCV prevention."
Heimer R et al. Recovery of infectious hepatitis C virus from injection paraphernalia: implications for prevention programs serving people who inject drugs. Journal of Infectious Diseases, 2017.