Needle exchange and
distribution programmes that provide sterile syringes have substantially reduced
transmission of blood-borne diseases including HIV, hepatitis B and hepatitis C
among people who inject drugs.
These viruses – especially
hepatitis C virus (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.
According to a study recently
published in The Journal of Infectious Diseases, sharing other drug preparation
paraphernalia such as cookers may not significantly contribute to HCV transmission among people who inject drugs.
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.
This contradicts previous studies, which have suggested that
cookers and filters can transmit HCV. For
example, a meta-analysis looking at HCV
incidence in people who inject drugs
found that sharing of drug preparation containers, of filters, of water or of
any combination of these items was strongly associated with an increased risk
of acquiring HCV, even if people did not share needles or syringes.
A study carried in Scotland between 2008 and
2010, which tested users of needle and
syringe programmes for recent HCV infection, found that sharing containers or
filters – but not water – was associated with an increased risk of acquiring
HCV, even if people did not share needles or syringes.
A previous German study found that in laboratory conditions, HCV
survived in water at room temperature at infectious levels for 21 days. The
researchers also found that infectious quantities of HCV could survive in the
water container, even if the water was emptied from it. Infectious quantities
of HCV could also be found in filters 48 hours after they had been exposed to
the virus.
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. To test which of these routes of transmission is more
plausible, researchers from Yale University designed an experiment to mimic
real-world injection practices.
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 people – who have had more opportunities to acquire HCV –
may be more likely to do this drug preparation. When the prepared drug is drawn
up into a syringe that has already been used, it could be contaminated by HCV
that remains in the syringe or the needle.
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.
HCV was seldom found in filters, but
this happened more often when detachable needles were used compared with fixed
needles. 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.
The authors say that the reason their
results differ from those of a previous laboratory experiment could be because
that experiment used 100 times the amount of HCV found in syringes in
real-world drug injecting conditions.
However, the findings do not rule out
the possibility that both drug sharing and the sharing of drug preparation
equipment could each independently lead to HCV transmission.
The researchers 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.
Daniel Raymond of the Harm Reduction Coalition
said that at a time when the demand for harm reduction services is growing
faster than funding, "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."
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