TB can cause illness in many ways, sometimes at the time of infection, but often years later.

Many people are exposed to TB as children, when they breathe in TB germs that have been expelled into the air from the lungs of a person infected with TB.

The TB germs multiply in the lungs, cause inflammation, and move to the lymph glands (the command centres of the immune system) in the lungs. This phase of the illness is called primary TB. The TB can spread and grow and cause disease. In most people who don’t have HIV, the body's immune system keeps the TB under control by forming a wall of scar tissue around it and most people (about 80%) clear the infection. In the remaining 20% of people, the TB will remain alive, but dormant. Although a person may not feel ill because of TB, the TB germ can remain alive within this contained area for many years, even decades, causing illness at a later time. This type of TB is usually called latent TB.

TB that is causing illness is called active TB.

TB that resurfaces from scar tissue and causes illness after a period of time is called reactivation TB.

Unlike most other opportunistic infections seen in people with HIV (so called because they take the opportunity of the body’s weakened immune defences to develop), TB can occur in people with normal CD4 cell counts and can be transmitted to other people, whether or not they have HIV.

A lot of people only find out that they have HIV because they have been diagnosed with TB. If you are in this situation, it might be helpful to know that finding out you have HIV will mean that you are now in a position to benefit from treatment and care that can keep you well. It is also worth noting that very effective treatment for TB is available, and people with HIV who had their TB treated have gone on to lead long and healthy lives.

NAM produces a lot of information on HIV treatment and living with HIV that you might find useful if you have just found out that you are HIV-positive. You can access this information via NAM’s website, www.aidsmap.com or contact us and we can send our other booklets to you.