More than 50,000 prisoners pass through the Australian correctional system each year and this number is growing, well ahead of the increase in the general population. The health status of prisoners (90 per cent of whom are male, 24 per cent of whom are indigenous) is poor and is linked to their lack of education and poor socio-economic status. They have high levels of mental illness, chronic and communicable diseases, and disability. Eighty per cent are smokers, 50 per cent drink alcohol at risky levels (this figure rises to 75 per cent for indigenous prisoners) and two-thirds reported using illicit drugs in the 12 months before prison.

One in four has a chronic health condition and 30 per cent of male prisoners and 40 per cent of female prisoners report having a mental health disorder. Prisoners are more likely to have experienced childhood sexual abuse and domestic violence and people with an intellectual disability are disproportionately represented among them. Australia spends $3.2 billion to keep people in prisons each year and if the rate of incarceration continues to grow at current rates there will need to be a $5 billion investment in capital spending in the next decade.

The average sentence length is 39 months, at which time the prisoner is returned to the community. If they are not to re-offend and quickly return to prison in a vicious and repetitive cycle, then it is necessary to ensure that during their sentence they receive appropriate rehabilitative services. In recent years Australian jurisdictions have invested in social rehabilitative programs that are described as high standard and evidence-based, although publicly available evidence of their value is lacking.

But little has been done to tackle the mental and physical health needs of prisoners who too often return to the community in poorer health. Ten per cent of prisoners inject drugs for the first time in prison and hepatitis C infection rates are as high as 40 per cent on discharge. Research from Western Australia shows that recently released prisoners, especially women, are at increased risk of hospitalisation and death from suicide, injury and the effects of alcohol or drug addiction. This work highlights the high healthcare needs of prisoners upon discharge and supports the allocation of resources for a range of healthcare services both within and outside the prison system.

The Australian Red Cross has called on the Council of Australian Governments to agree to set targets on a state and territory basis with a five-year goal to cut incarceration rates to 2000 levels. It advocates investing in community-based initiatives that tackle vulnerability and disadvantage.

The prison environment provides an opportunity to address the physical and mental health needs of prisoners that may have remained unaddressed in the community. But success in tackling poor prisoner health ultimately depends on reducing the same social inequalities that lead to offending behaviour.

The issue for politicians is how to explain the community advantages of investing in prison health and rehabilitation programs without being seen to take resources away from those perceived as more deserving and without jeopardising the modern political desire for governments to be seen to be ''tough on crime''. One approach is to highlight the cost-effectiveness of early intervention and how these programs reduce recidivism.

Tackling these issues is not easy. It is now 10 months since Chief Minister Katy Gallagher announced an Australian-first needle exchange program for the ACT prison. However protracted negotiations over prison guards' concerns mean that the program has yet to be implemented. In the interval at least two and maybe 20 new cases of hepatitis C have been transmitted inside the jail.

When these prisoners are released, it will be necessary to ensure that they receive healthcare and comply with their medication regimes if they are not to place others at risk of infection.

With the constant interchange between prisons and the community, the health problems and medical conditions experienced in custody become issues of public health for the wider community. Just as chronically ill patients need effective discharge planning when they leave hospital, so prisoners with chronic conditions, mental illness, addictions and infectious diseases such as hepatitis and HIV/AIDS also need a discharge plan to ensure community linkage and continuity of clinical care.

Dr Lesley Russell is a senior research fellow at the Australian primary health care research institute at the Australian National University.