Tuberculosis Basic Information
Tuberculosis (tuberculosis) disease is caused by a bacterium called Mycobacterium tuberculosis. The bacteria usually attack the lungs, but tuberculosis bacteria can attack any part of the body such as the kidney, spine, and brain. If not treated properly, tuberculosis disease can be fatal.
Tuberculosis is spread through the air from one person to another. The tuberculosis bacteria are put into the air when a person with active tuberculosis disease of the lungs or throat coughs, sneezes, speaks, or sings. People nearby may breathe in these bacteria and become infected.
Not everyone infected with tuberculosis bacteria becomes sick. As a result, two tuberculosis-related conditions exist: latent tuberculosis infection and active tuberculosis disease.
Latent tuberculosis Infection
Tuberculosis bacteria can live in your body without making you sick. This is called latent tuberculosis infection (LtuberculosisI). In most people who breathe in tuberculosis bacteria and become infected, the body is able to fight the bacteria to stop them from growing. People with latent tuberculosis infection do not feel sick and do not have any symptoms. The only sign of tuberculosis infection is a positive reaction to the tuberculin skin test or special tuberculosis blood test. People with latent tuberculosis infection are not infectious and cannot spread tuberculosis bacteria to others. However, if tuberculosis bacteria become active in the body and multiply, the person will get sick with tuberculosis disease.
Tuberculosis bacteria become active if the immune system can’t stop them from growing. When tuberculosis bacteria are active (multiplying in your body), this is called tuberculosis disease. Tuberculosis disease will make you sick. People with tuberculosis disease may spread the bacteria to people they spend time with every day. Many people who have latent tuberculosis infection never develop tuberculosis disease. Some people develop tuberculosis disease soon after becoming infected (within weeks) before their immune system can fight the tuberculosis bacteria. Other people may get sick years later, when their immune system becomes weak for another reason.
For persons whose immune systems are weak, especially those with HIV infection, the risk of developing tuberculosis disease is much higher than for persons with normal immune systems.
Who Should Not Be Vaccinated
BCG vaccination should not be given to persons who are immunosuppressed (e.g., persons who are HIV infected) or who are likely to become immunocompromised (e.g., persons who are candidates for organ transplant).
BCG vaccination should not be given during pregnancy. Even though no harmful effects of BCG vaccination on the fetus have been observed, further studies are needed to prove its safety.