A higher than expected incidence of HIV infections, and a high incidence of hepatitis C virus infections has been found amongst injecting drug users in London, according to a study published in the November 13th online edition of the British Medical Journal.
Compared to some other European countries the United Kingdom has a low prevalence of both HIV and hepatitis C virus amongst injecting drug users. This is attributed to the harm reduction measures introduced in the late 1980s, including the widespread introduction of needle exchange.
Investigators wished to determine the incidence of HIV and hepatitis C virus amongst new injecting drug users in London.
In 2001, a total of 428 injecting drug users under 30 years of age who had been injecting drugs for less than six years, were recruited from community settings in London and Brighton. Samples were provided for baseline HIV and hepatitis C virus testing and individuals provided demographic details and information about their injecting behaviour and risk activity to researchers. Follow-up was provided for a year.
Almost all (91%) were recruited in London, the mean age was 27 years and 29% were women. Almost two-thirds (61%) of the sample had been injecting for less than four years, and the median frequency of injecting was 2.5 times a day.
Opiate injection was reported by 71% of the sample, but 53% said that they had injected crack or cocaine.
High levels of injecting risk were reported, with 24% of individuals at baseline saying that they had shared needles and syringes and 54% reporting the sharing of drug use paraphernalia.
At baseline, 44% of individuals had antibodies to hepatitis C virus and 4% were HIV-positive.
A total of 70% of the sample provided a year’s follow-up. There were no significant differences in demographic or risk behaviour between individuals followed-up and those lost to follow-up.
The incidence of hepatitis C was 41.8 cases per 100 person-years and the incidence of HIV was 3.4 per 100 person-years.
“The incidence of hepatitis C virus is…high, and of HIV higher than expected,” write the investigators. They add that their findings “are corroborated by ongoing surveillance data, and suggest that transmission may have recently increased.” Indeed, the investigators note that the incidence of HIV amongst injecting drug users was comparable to that seen in gay men attending sexually transmitted infections clinics in London.
Explanations offered by the investigators for the increased incidence of HIV include the greater use of crack cocaine, and an increase in the size of the population of injecting drug users.
An absence of targets to prevent the spread of blood-borne viruses amongst injecting drug users in recent government strategies is also noted by the investigators.
They conclude, “increasing the coverage of syringe exchange and provision of drug treatment is only part of the solution. Innovative strategies are required, specific to hepatitis C virus and HIV, to change behaviour and to deliver health education messages and harm reduction strategies early enough to make a difference.”
Judd A et al. Incidence of hepatitis C virus and HIV among new injecting drug users in London: prospective cohort study. Br Med J, November 13th, 2004.