Tuberculosis (TB) is a contagious disease that is caused by the bacterium mycobacterium tuberculosis. The disease primarily affects the lungs, although the intestines, joints, and other parts of the body may also become infected. It is spread mainly by inhalation of the germs, and occasionally by ingestion through contaminated foods and utensils. Symptoms include fever, weakness, loss of appetite, and, in the pulmonary form, cough and sputum. A vaccine that confers partial and temporary immunity to is given by the World Health Organization to high-risk children. The number of TB, once ubiquitous, has decreased with improved sanitation, early detection through X rays and skin tests, and antituberculosis drugs, but in the late 1980s the number of cases began to rise, particularly among AIDS patients, the poor, and immigrants from developing countries. Another problem was the spread of strains resistant to isoniazid, the drug used in TB treatment.

TB is spread when people who harbor TB germs cough, sneeze, or speak, and send their germs into the air. People who breathe these germs into their lungs can then become infected. People who breathe in TB germs usually have had very close contact with someone, usually a friend or co-worker, who has the disease. TB is not, however, spread by dishes, drinking glasses, sheets, or clothing.