HIV/Aids and TB infection/disease share many common features, though completely diferent in the route of transmission. X They are over‑represented in underprivileged populations, thus showing a much higher prevalence in the prison population than in the community. HIV prevalence in prison is up to 25 times and TB prevalence up to 100 times higher than in the community at large;4 prisons favour both HIV transmission (see previous chapter) and TB transmission; prison conditions such as overcrowding, poor ventilation, weak nutrition and inadequate or inaccessible medical care fan the spread of TB inside prisons; prisons act as TB reservoirs, pumping the disease into the community through staf, visitors and inadequately treated released prisoners; and factors favouring the spread of TB favour also the spread of drug‑resistant TB.5 Hence, prisons must be regarded as epidemiological epicentres for the TB epidemic, just as they are (as mentioned earlier) for the HIV/Aids epidemic: prisons are epidemiological epicentres for the dual epidemic and must be acknowledged as such by the community. X TB is a poverty‑driven disease, and drug addiction in many countries is a major cause of HIV infection, which is also associated with and/or leads to poverty. Both infections, HIV and TB, are accompanied by social stigmatisation and further marginalisation. XA rapidly increasing number of individual patients are afected by both infections; and, in both infections, T‑cell‑mediated immunity is afected, so each of them worsens the clinical course of the other. Whereas not more than 10% of immune‑competent persons infected with TB develop clinical manifest of the disease, there is a 30 times higher likelihood of manifest of TB disease in HIV‑infected persons. The problem is further aggravated by the fact that diagnosis of TB disease in immune‑compromised persons is much more difcult than in immune‑competent patients because of lower reliability in sputum microscopy diagnosis of infectious pulmonary TB alongside the greater prevalence of extra‑pulmonary TB, resulting in less reliable X‑ray diagnosis. Moreover, the combined treatment with antiretroviral drugs for HIV/Aids and TB, particularly the treatment of drug‑resistant TB, is difcult and challenging due to the many drug interactions and adverse side‑efects, and it may be less efective. 4. WHO: Tuberculosis in prisons (web page) at www.who.int/tb/challenges/prisons/en/. 5. Ibid. Prison health care and medical ethics Page 64