Extensively drug-resistant (XDR) tuberculosis: a new threat to global public health

Throughout the world, eight million people develop active tuberculosis (TB) each year and 5,000 of them will die from this disease every day. Although treatable and curable, globally about 3% of all newly-diagnosed patients have multi-drug-resistant TB (MDR TB) making their treatment complicated, expensive and uncertain. In September 2006 the World Health Organization announced a further worsening of the MDR TB pandemic with multiple reports in all regions of the world of the emergence of extensively resistant (XDR) strains of TB resistant to virtually all antituberculosis drugs. XDR TB may become the primary health scourge of the 21st century and in this brief report, the current status of our understanding of this new peril is discussed.