If TB occurs following the initial infection, it is referred to as primary TB, which is common in children and HIV-infected individuals. Pulmonary TB is the common and most contagious form of active TB. TB can occur in almost any other part of the body, including the lymph glands, lungs, joints, bones or intestines, and is called extra-pulmonary TB. In HIV-infected TB patients, TB often affects more than one organ, and pulmonary and extra-pulmonary TB commonly co-exist.