Incidence of Hepatitis C Virus and HIV Among New Injecting Drug Users in London: Prospective Cohort Study

The low prevalence of HIV among injecting drug users (IDUs) in England in the 1990s was attributed in part to harm-reduction interventions introduced in the 1980s. The prevalence of hepatitis C virus was thought to be relatively low compared to other countries, around 40 percent overall and 15 percent among IDUs who had been injecting drugs for less than six years.

In 2001, the authors recruited 428 IDUs below age 30 who had been injecting for six or fewer years for a prospective cohort study to estimate the incidence of hepatitis C and HIV. The participants, recruited from London (91 percent) and Brighton, completed interviewer-administered questionnaires and provided blood and oral fluid specimens for testing. At baseline, prevalence of hepatitis C antibody was 44 percent; prevalence of HIV antibody was 4 percent. Twenty-four percent at baseline reported injecting in the previous four weeks with needles and syringes used by someone else; 53 percent reported sharing injection paraphernalia. Participants were followed up 12 months later.

The researchers found that the incidence of hepatitis C virus and HIV among new IDUs in London were 41.8 and 3.4 cases per 100 person years, respectively. The incidences were higher than expected, and the findings suggest that transmission may have recently increased.

Possible explanations for the rising incidence, the authors suggested, include changes in patterns of injecting drug use, with greater injection of crack and more injecting risk behaviors in newer IDUs than in those injecting in the early to mid-1990s.

"In addition there may have been increases in the size of the population of injecting drug users over and above any increase in protective interventions," according to the researchers.

"Specific targets to prevent bloodborne viruses among injecting drug users have been absent from the UK government's drug strategy in the past five years, and there has been little targeted health education and prevention campaigns," the authors wrote. "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 to HIV, to change behaviour and to deliver health education messages and harm reduction strategies early enough to make a difference," they concluded.

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