Their study was published as part of series in the Lancet on HIV and related infections in prisoners, which was also presented at this month's International AIDS Conference in Durban, South Africa. The Series notes that with an estimated 30 million people passing in and out of prisons every year, prisoners will be key to controlling HIV and tuberculosis epidemics worldwide.

The Bristol researchers' contributed to a study looking specifically at the 15 UNAIDS-designated countries of Eastern Europe and Central Asia (EECA) that gained independence from the Soviet Union in 1991.*

Study co-author Professor Peter Vickerman, from the School of Social and Community Medicine, said: "Despite global reductions in HIV incidence and mortality, this is the only region where both continue to rise. HIV transmission in EECA is fuelled primarily by injection of opioids, with harsh criminalisation of drug use that has resulted in extraordinarily high levels of incarceration. Consequently, people who inject drugs, including those with HIV, hepatitis C virus, and tuberculosis, are concentrated within prisons.

"Mathematical modelling for Ukraine suggests high levels of incarceration in EECA countries facilitate HIV transmission among people who inject drugs, with 28–55 per cent of all new HIV infections over the next 15 years predicted to be attributable to heightened HIV transmission risk among currently or previously incarcerated people who inject drugs."

The study argues boosting opioid agonist therapies in prisons, and maintaining treatment after release, would give the greatest HIV transmission reduction in people who inject drugs.

Professor Vickerman said: "Additional analyses also suggest at least six per cent of all incident tuberculosis cases, and 75 per cent of incident tuberculosis cases in people who inject drugs are due to incarceration.

"Interventions that reduce incarceration itself and effectively intervene with prisoners to screen, diagnose, and treat addiction and HIV, hepatitis C virus, and tuberculosis are urgently needed to stem the multiple overlapping epidemics concentrated in prisons."

Paper:

'The perfect storm: incarceration and the high-risk environment perpetuating transmission of HIV, hepatitis C virus, and tuberculosis in Eastern Europe and Central Asia' by Frederick Altice et al in The Lancet