It was only by coincidence that Harvard sent scientists to determine the extent of drug resistance in diseases in South Africa, and discovered the new TB strain referred to as extreme drug-resistant TB, or XDR-TB. If the study had been in some other parts of Africa, the strain might not have been identified because there are no research facilities to make diagnoses or monitor numbers.
Nunn noted that the situation was dire, and said that of the 9 million known cases of TB worldwide, as many as 2 percent could be XDR-TB.
"This is raising the specter of something that we have been worried might happen for a decade - the possibility of virtually untreatable TB," Nunn said. It is particularly worrisome, Nunn added, that the disease is very transmittable, especially in small spaces such as airplane cabins.
According to Nunn, 100 percent of XDR-TB patients who could be tested were HIV positive, and the spread of this strain in Africa could shatter any hope of containing the AIDS pandemic currently afflicting parts of the continent. A cluster of TB cases occurred in KwaZulu-Natal in South Africa, and 221 of the 544 patients studied had TB strains that were resistant to the two common drugs, rifampicin and isoniazid. Fifty-three of the patients had XDR-TB, and 52 of them died from the condition, which casts a pall over the use of antiretroviral (ARV) drug treatments to keep the millions of HIV patients alive until a cure can be found.
"There is no point in investing hugely in ARV programs if patients are going to die a few weeks later from extreme drug-resistant tuberculosis," Nunn said.
Cases of XDR-TB have been discovered in the U.K., Eastern Europe and even the United States, where the best drug treatments in the world are available. In March, the U.S. Centers for Disease Control reported 64 cases of XDR-TB, 21 of which were fatal. Experts say that despite the significant number of known XDR-TB cases found worldwide, an even greater number may be going unrecognized.
Part of the problem is that all TB drugs are old -- as it was thought conquered more than 50 years ago -- and drug companies do not invest in TB drugs because it is regarded as a disease of Third World countries. As the AIDS crisis has brought more attention to the inadequacy of general medical treatment in Africa, public-private partnerships have been put together in order to find and develop new drugs, but they have yet to produce results.
The XDR-TB crisis will be addressed tomorrow in an emergency two-day meeting of WHO officials and international TB experts in Johannesburg, South Africa.
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