XDR-TB stands for “Extensively Drug-Resistant Tuberculosis” (though some reports have “extreme drug-resistant”), a term that was coined in a report by the US Centers for Disease Control and the World Health Organization that was published on World TB Day in March 2006. It refers to an intensification of a severe medical problem that has been growing for two decades — the evolution of strains of TB resistant to the drugs available.
The term for an earlier stage of the evolution of drug resistance was MDR-TB, “Multiple Drug Resistant Tuberculosis”. The difference between this and the new form is that sufferers from XDR-TB are resistant not only to the usual front-line drugs for the disease but also to three or more of the six second-level ones, making it extremely difficult to treat. It has been reported from various countries, but the main focus of concern is South Africa.
There is hope that some new drugs in the pipeline may be effective against it.
The combination of Aids and XDR-TB found in a quarter of patients in Natal carries a mortality rate of 100 per cent.
Daily Telegraph, 7 Sep. 2006
Dr. Mario C. Raviglione, who directs the World Health Organization’s tuberculosis program, said in an interview that “nobody at the moment can be considered an expert” about the XDR-TB problem. But he said that the XDR-TB situation is “extremely scary.”
New York Times, 5 Sep 2006