A serious illness that mainly affects the lungs and is caused by bacteria.

Tuberculosis, often called TB, is caused by bacteria that mainly infect the lungs. The bacteria spread when a person with TB coughs, sneezes or sings. If the body controls the infection, the illness is called latent TB. If the body can't control the infection, that stage is called active TB.

Early symptoms of TB are fever, tiredness and cough. Symptoms of active TB include cough with or without mucus or blood, chest pain, and pain with breathing. Symptoms also may include weight loss, tiredness and night sweats.

Medicines that kill bacteria are usually combined to treat TB. Latent TB may be treated with medicine for three or four months. Active TB may need longer treatment, often 4 to 9 months.