Introduction: Injecting drug users (IDUs) represent 41.6% of the total cohort of HIV-infected patients in Ireland. Between January 1999 and December 2000, referrals to the largest tertiary centre for HIV infection in Dublin have increased dramatically. This has occurred on a background of a reduction in the overall incidence of HIV infection in Ireland between 1990 and 1998. Here we describe the changing epidemiology of HIV disease in IDUs and explore potential aetiological factors.
Methods: This is a retrospective study, collecting all data relating to new HIV diagnoses occurring in IDUs, referred to the GenitoUrinary Medicine and Infectious Diseases (GUIDE) clinic between 1987 and 2000. We calculated 6-month incidence rates of new HIV diagnoses in IDUs referred to the GUIDE clinic and performed a more detailed analysis of those patients diagnosed between January 1999 and December 2000, documenting age, sex, time and place of diagnosis, drug use history and primary drug of misuse, needle sharing history, attendance at a drug treatment clinic, prior HIV testing history, hepatitis B and hepatitis C status, and CD4 cell counts and HIV RNA levels at diagnosis.
Results: The number of new HIV diagnoses in IDUs increased fivefold between 1995 and 2000. Moreover, 40% of patients diagnosed since then have been under 22 years old. There has also been a significant reversal of the initial male to female ratio seen in the initial epidemic of the 1980s.
Conclusion: There has been a significant increase in the incidence of HIV infection in IDUs between 1995 and 2000. Similar trends have been described recently in other risk groups. The aetiology of these trends is multifactorial, and a multidisciplinary, rejuvenated approach is required to focus on improving health education to reduce both sexual and needle sharing practices.