Introduction to tuberculosis

Tuberculosis (TB) is uncommon in Australia. It should be considered in high-risk patient groups (eg people from high-prevalence countries), and anyone with an undiagnosed febrile or wasting illness, or a persistent cough.

Primary Mycobacterium tuberculosis infection is usually contained by the immune system (see Latent tuberculosis), but it may produce active disease in the form of a primary tuberculous pleural effusion, or spread to produce miliary (disseminated) or central nervous system TB. At least 90% of individuals infected with M. tuberculosis do not develop active disease.

Postprimary disease, caused by reactivation of latent TB, usually occurs within 5 years of initial infection, and most commonly produces pulmonary TB.

TB can produce a wide range of clinical syndromes in addition to the classic upper lobe cavitary pulmonary infection. Risk factors for extrapulmonary TB include childhood, HIV infection and immune compromise.