Some people who are infected with TB successfully fight off the bacterium and clear it completely from their body. In others, the TB bacterium lingers in the body but does not cause symptoms and cannot be passed on to others, a so-called latent TB infection. Some people develop active TB disease. This may happen soon after initial infection, or it may occur later, when the person’s immune system becomes weak for another reason. Active TB infection mainly affects the lungs (pulmonary tuberculosis) and may cause the following symptoms:

• bad cough lasting three weeks or longer
• coughing up discolored or bloody sputum
• unintended weight loss
• fatigue or weakness
• low-grade fever
• chills
• night sweats
• loss of appetite
• pain in the chest with breathing or coughing

Tuberculosis may also target other areas of the body, including the joints, bones, urinary tract, central nervous system, muscles, bone marrow, and lymphatic system. When TB occurs outside the lungs (extrapulmonary tuberculosis), the symptoms vary depending on which body regions are infected. In rare cases, TB may spread throughout the entire body simultaneously.