People living with HIV within a prison system face a unique set of circumstances: those of providing for healthcare needs in a difficult environment to a crowded population, many with mental health, drink and drug abuse histories. Stigma and discrimination within the UK prison system causes many HIV-positive prisoners not to disclose their status. Although the UK has officially relatively low numbers of HIV-positive prisoners, there is evidence that these figures bear little relation to the actual levels of blood-borne infections in many of Britain's prisons. The prevention, testing and treatment of HIV and hepatitis B and C must become a priority.

Prisoners are up to five times more likely to contract HIV than the general population, and more likely still to be infected with Hepatitis C and other blood-borne viruses and infections. The Department of Health's anonymous 1997 sero-survey, generally considered to be an under-estimate, point to HIV rates among male prisoners four times that of the general population. Women prisoners were 13 times more likely to test positive for HIV than the wider population.

The number of prisoners in England and Wales has increased by more than 25,000 in the last ten years, reaching 76,524 in July 2005 (Home Office), 4 570 of whom were women. In October 2005 the prison population in Scotland was 6 929 (Scottish Prison Service) and 1 394 in Northern Ireland (Northern Ireland Prison Service).

At the start of 2005 there was a total UK prison population of nearly 85,000 or one in 700 of the entire population, the highest rate in Western Europe.

All but 30% of these prisoners will be released back into the community at some stage. Almost 200,000 people will pass through prison annually, impacting on an estimated 1.5 families and friends. Health problems created in prison then become problems for the community as a whole.

The nature of the prison population is also changing. Research published in The Lancet (Fazel) for the first time looked at the long-term trends in suicide rates in English and Welsh prisons. The overall suicide rate among prisoners was five times greater than the general population, and in the 15-17 year-old age group, 18 times higher. The study points to the shift of care from psychiatric hospitals to community-based services, including eventually prison.

Together with mental health problems (around 70 per cent of prisoners have a diagnosable mental health illness), many prisoners have faced social exclusion and exclusion from education. More than half of the prisoners have a reading ability at or below that of an average 11 year-old, according to the Prison Reform Trust (Factfile May 2005). The UK prison population is a marginal and vulnerable group, disproportionately vulnerable to blood-borne infections.