Tuberculosis infection is acquired by inhaling small droplets infected with mycobacteria that are expelled by a patient with pulmonary tuberculosis. The body can contain the mycobacteria by making a cellular immune response. This stage is called latent tuberculosis infection (LTBI) and can be measured either by a tuberculin skin test or by an interferon gamma release assay (blood test). About 10% of persons with LTBI will develop active tuberculosis (disease) in their lifetime, half of them within the first 1-2 years after infection.
Symptoms of pulmonary tuberculosis are coughing, weight loss, night sweats and persistent fever. Tuberculosis in other organs will present with symptoms related to that part of the body. The diagnosis of active tuberculosis is based on the set of symptoms, additional investigations (e.g. chest radiography) and preferably by culturing the mycobacteria from the sputum or other body fluids.
Tuberculosis is treated with 3-4 drugs during 6 months. The treatment may be up to 20 months if the M. tuberculosis bacteria is resistant to isoniazid and rifampicin (multidrug-resistant or MDR TB). Persons with LTBI are treated with isoniazid and rifampicin for 3 months or isoniazid alone for 6 months.