Tuberculosis, or TB, is caused by bacteria that usually attack the lungs but may also affect other parts of the body such as the kidneys or brain, according to the Centers for Disease Control and Prevention. People with TB may have latent infections or infectious TB disease.
People may have TB bacteria in their bodies without presenting symptoms of the illness, a condition known as latent TB infection, advises the CDC. People with latent TB infections cannot spread TB bacteria to others unless the TB becomes active in the body and develops into TB disease. TB disease occurs when the body cannot stop the TB bacterium from growing and multiplying, at which point a person suffering from the disease becomes infectious. TB disease may be fatal, and risk factors include HIV infection, diabetes, and alcohol or drug abuse.
People with TB disease may infect others by coughing, sneezing or speaking, leading others to breathe in the bacteria, states the CDC. TB is not spread through other types of contact such as sharing toothbrushes, shaking someone's hand or kissing. The symptoms of TB include a bad, prolonged cough, chest pain, coughing up blood, weight loss and lack of appetite. Doctors diagnose TB through the use of TB skin tests or blood tests.