Important insights into the continued spread of hepatitis C
among injecting drug users are provided by two studies published in the online
edition of the Journal of Infectious
An international team of investigators showed that
infectious quantities of hepatitis C could survive on inanimate surfaces for up
to seven days. However, the virus can be rendered inactive by commercially
available disinfectants, or heating to a temperature of 65-70°C
for approximately 90 seconds.
In a separate study, French investigators detected the virus
on 80% of alcohol swabs obtained from injecting drug users. They suggest that the swabs may be
shared by users, risking the transmission of hepatitis C.
Holly Hagan of the New York University College of Nursing in
an accompanying editorial stated: “The studies contribute new knowledge to our
understanding of the mechanisms by which HCV [hepatitis C virus] may be
transmitted among PWID [people who inject drugs] via injection-related
There are an estimated 130 million hepatitis C infections
worldwide. Hepatitis C is a blood-borne infection and a major mode of
transmission is injecting drug use. Needle and syringe exchange programmes have
been introduced in many countries to control the epidemic. The have been highly
effective at preventing new HIV infections, but hepatitis C transmissions still
This is possibly because viral load tends to be high in
individuals with chronic hepatitis C infection, and even small quantities of
contaminated blood are potentially infectious.
A team of investigators led by Juliane Doerrbecker wished
to establish a clearer understanding of the survival of the virus, and the
effectiveness of disinfectants and heat at rendering the virus non-infectious.
Steel discs were contaminated with infectious quantities of
hepatitis C which were then allowed to dry. Reassuringly, commercially
available disinfectants were also shown to have “a high virucidal efficacy
Tests also showed that infectious quantities of hepatitis C
of approximately 30 TCID50/ml could still be detected on inanimate
surfaces up to seven days after contamination. However, the investigators
emphasised that “all tested biocides were able to inactivate HCV infectivity to
The investigators then examined the effect of heat on the
virus. Spoons and/or cookers are used to heat diluted heroin into solutions.
The liquid is then drawn into a syringe, potentially contaminating the spoon
if hepatitis C-infected blood is present in the syringe. The investigators
therefore contaminated spoons with the virus, which were then heated to various
temperatures using tea candles.
Infectivity started to decrease at temperatures of
approximately 50°C. Levels of the virus fell below the limit of detection when
temperatures reached 67-70°C. It generally took between 80 to 95 seconds for
heating to produce small bubbles in the spoon.
“Reusing HCV contaminated cookers could lead to infection even if
using sterile syringes,” comment the investigators.
Holly Hagan emphasised that injecting drug users rarely heat spoons
for more than 15 seconds.
In separate research, Dr Vincent Thibault and his colleagues collected
drug-using paraphernalia from individuals known to be infected with hepatitis C.
The used paraphernalia included syringes, filters and water cups, swabs for
cleaning of skin before injecting and pads employed to stop bleeding after
withdrawal of needles. A total of 160 pieces of equipment were collected.
The virus was detected on 44% of the pooled materials.
A further 620 items used by individuals of unknown infection status
were also obtained. Approximately 83% of the pools obtained from swabs had
detectable hepatitis C. Moreover, viral load was highest (above 3 log10
iu/ml) within these swab pools.
Hepatitis C was also commonly detected in syringes, but viral load tended
to be at low levels (12 to 890 iu/ml).
The investigators therefore believe that there is “a higher chance for
PWID to be contaminated though sharing of a tainted spoon rather than a tainted
They note that blood was often visible on swabs. The researchers
therefore suggest that transmission of the virus could occur if swabs were
being used inappropriately. “The chaotic and rushed atmosphere of the injection
setting, where swab sharing and mixing could take place, is…an important factor
that should be considered.”
Holly Hagan believes the two studies have important implications for
hepatitis C prevention programmes. “Cleaning cookers or perhaps impregnating
injection equipment with safe biocides may help reduce the incidence of new
infections. Promoting safe swab use to emphasize avoidance of reuse seems a