Tuberculosis (TB) is the leading cause of death among curable infectious diseases. About nine million new cases and nearly two million deaths from TB are estimated to occur around the world every year. It is caused by bacteria belonging to the Mycobacterium tuberculosis complex and may affect almost any part of the body. The most common form is pulmonary TB. Non-respiratory forms of TB are more common in young children in communities with connections to areas of the world with high prevalence, and in those with impaired immunity. Transmission occurs through infectious droplets coughed by patients suffering from pulmonary TB. Disease is usually curable with a combination of specific antibiotics. Latent TB infection may reactivate in later life particularly if an individual’s immune system has become weakened, for example by disease (e.g. HIV-AIDS), certain medical treatments (e.g. cancer chemotherapy, corticosteroids) or in old age. Disease can be prevented by immunisation with the BCG (Bacille Calmette Guerin) vaccine, which contains live attenuated bacteria derived from M. bovis in lyophilised formulation.