Tuberculosis

What is it?

Tuberculosis (TB) is an infectious disease caused by Mycobacterium tuberculosis. This pathogen is a slow-growing organism so treatment requires the use of multiple drugs for a prolonged period of time. Worldwide, TB is still the leading cause of death due to infection, killing more than 3 million people a year. TB may affect many body organs, but it primarily affects the lungs. It is spread through the air from person to person through lung secretions such as sputum (spit or phlegm) or aerosols released by coughing, sneezing, laughing or singing. Most of those who become infected with M. tuberculosis manage to confine the microorganisms to a few cells in their body, where they stay alive in an inactive form. This inactive or latent TB infection does not make the patient sick or infectious and, in most cases, it does not ever progress to cause active or symptomatic tuberculosis.

However, some patients - especially those with damaged or compromised immune systems - may proceed directly from initial TB infection to active tuberculosis. Approximately 10% of infected people develop active TB, usually within the first 5-7 years after infection.

TB is not a common disease in Australia and the incidence of TB in Australia has remained stable since 1985, at approximately 5.4 cases per 100,000 population. The risk of infection is higher in migrants from high incidence countries and indigenous Australians at 21.7 and 8.1 cases per 100,000 population, respectively.