Symptoms and Signs of Tuberculosis

Doctor's Notes on Tuberculosis

Tuberculosis (TB) is an infectious disease caused by bacteria. Initial infections usually have no symptoms in people or, if people do develop symptoms, the symptoms are nonspecific such as fever and an occasional dry cough. However, as the disease progresses slowly, symptoms such as weight loss, loss of energy, fever, a productive cough, poor appetite and night sweats may develop. The disease may go dormant for years, but when it returns, symptoms may include a cough that produces increased mucus, the patient may cough up blood and the symptoms of fever, loss of appetite, weight loss and night sweats return. Some patients develop infection in the lungs that spreads into the pleural space which causes chest pain. Other patients develop tuberculosis in other organs such as lymph nodes, bones and/or joints, meninges, the genitourinary tract and the outside lining of the gastrointestinal tract. Symptoms of pain and discomfort can be associated with the location of the infection and may produce symptoms like those described above.

Tuberculosis is caused by a rod-shaped bacterium, Mycobacterium tuberculosis. The bacteria are transmitted person-to-person by inhaled droplets that contain the bacteria. In the lungs, the body’s macrophage engulfs the bacteria. Sometimes the macrophages cannot kill the bacteria and then the bacteria can be transported via the lymph system or blood inside a macrophage to other body organs. Occasionally, the bacteria go dormant (latent TB infection) then reactivate so that the bacteria multiply and thus reactivate tuberculosis symptoms.

Medical Author:
Medically Reviewed on 3/11/2019


Kasper, D.L., et al., eds. Harrison's Principles of Internal Medicine, 19th Ed. United States: McGraw-Hill Education, 2015.