How do people become infected with XDR-TB?
People who are ill with pulmonary TB (i.e. TB of the lungs, the site most commonly affected) are often infectious and can spread the disease by coughing, or sneezing, or simply talking, as this propels TB bacteria into the air. A person needs only to breathe in a small number of these germs to become infected (although only a small proportion of people will become infected with TB disease). Sometimes the bacteria are already drug resistant if they come from a person who already has drug-resistant TB. A second way of developing MDR-TB or XDR-TB is when a patient’s own TB develops resistance. This can occur when anti-TB drugs are misused or mismanaged. This happens when TB control programmes are poorly managed, for example when patients are not properly supported to complete their full course of treatment; when health-care providers prescribe the wrong treatment, or the wrong dose, or for too short a period of time; when the supply of drugs to the clinics dispensing drugs is erratic; or
