It is estimated by WHO that one-third of the 40 million people living with HIV/AIDS worldwide are co-infected with TB. People with HIV are up to 50 times more likely to develop TB in a given year than HIV-negative people.

Another aspect of the resurgence of TB is the development of drug-resistant strains. These strains can be created by inconsistent and inadequate treatment practices that encourage bacteria to become tougher. The multi-drug resistant strains are much more difficult and costly to treat and multi-drug resistant TB (MDR-TB) is often fatal. Mortality rates of MDR-TB are comparable with those for TB in the days before the development of antibiotics.

The dangers of inconsistent therapy were picked up by Baroness Vivien Stern addressing the “Tuberculosis among Prisoners Interdisciplinary Expert Meeting on Prevention and Control” in St Petersburg, Russia on 25-27 November, 2002.

She said in her keynote speech, “We know that people leave prison – in Russia 350,000 people leave prison every year. We know that many released prisoners undertaking treatment in prison do not carry on with the treatment on release. In one Oblast (province) in Russia 75% of released TB prisoners did not carry on with the treatment.”

She reported that in the Ukraine there is a gradual integration of penitentiary medical service into the structure of state health care. In Latvia the Ministry of Welfare inspects prisons to see if they are reaching the level of civilian health care. She called for Russia to strengthen its links between prison health and public health. She said that only Norway, France and latterly England and Wales had prison health care under the control of the Health Ministry.

HIV/AIDS and TB are so closely connected that the term “co-epidemic” or “dual epidemic” is often used to describe their relationship. HIV affects the immune system and increases the likelihood of people acquiring new TB infection. It also promotes both the progression of latent TB infection to active disease and relapse of the disease in previously treated patients. TB is one of the leading causes of death in HIV-infected people. In prisons, especially in the developing world TB and HIV fuel each others grip on an incarcerated community.

HIV infection is the most potent risk factor for converting latent TB into active TB, while TB bacteria accelerate the progress of AIDS infection in the patient.

Many people infected with HIV in developing countries develop TB as the first manifestation of AIDS. The two diseases represent a deadly combination, since they are more destructive together than either disease alone.

• TB is harder to diagnose in HIV-positive people.
• TB progresses faster in HIV-infected people.
• TB in HIV-positive people is almost certain to be fatal if undiagnosed or left untreated.
• TB occurs earlier in the course of HIV infection than many other opportunistic infections.

According to WHO, TB infection is currently spreading at the rate of one person per second. It kills more young people and adults than any other infectious disease and is the world's biggest killer of women. In 1993, WHO declared TB to be "a global health emergency". Every year 8–10 million people catch the disease and two million die from it. About a third of the world's population, or around two billion people, carry the Mycobacterium tuberculosis bacterium but most never develop the active disease. Around 10% of people infected with TB actually develop the disease in their lifetimes, but this proportion is changing as HIV severely weakens the human immune system and makes people much more vulnerable.