Wednesday, March 21, 2007

Resistant TB on the march

Bad news from South Africa. A nasty strain of TB that's resistant to virtually every antibiotics is becoming more and more widespread. While multi-resistant TB (MDR-TB) have been around for a while, this new strain of extremely/extensively drug-resistant tuberculosis (XDR-TB) have only been known since 2005. Unfortunately it is spreading

Dr. Karin Weyer of the South African Medical Research Council said XDR-TB has been found in more than 40 hospitals in all nine provinces of South Africa, The Times said.

The XDR-TB bacteria have been linked to HIV/AIDS in earlier studies, making health officials not only fear for their TB programs, but also their HIV programs.

"This is an issue of grave worldwide importance," said Friedland. "MDR and XDR carry the danger of blunting or reversing the success of TB programs and the roll-out of anti-retroviral therapies for HIV where they are desperately needed in resource limited settings. Urgent intervention is necessary, especially now that we know that MDR tuberculosis is far more prevalent than previously thought and that XDR tuberculosis has been transmitted to HIV co-infected patients and associated with high mortality."

According to the second article, there haven't been any new approvals of TB drugs in 40 years, so new treatments are desperately needed, as are new diagnostic tests - they still use the same ones that were used in 1882, according to Gerald Friedland, M.D., director of the AIDS Program at Yale and Professor in the Departments of Medicine and Epidemiology and Public Health.

And it's not only South Africa that sees the XDR-TB strains. XDR-TB is defined by the WHO as

a form of the bacteria Mycobacterium tuberculosis that is resistant to standard oral drugs, to newer fluoroquinolones and to one of three injected drugs.

So far it has been reported in 28 countries, but mostly in China, India, and Russia.

And as a personal note to Dr. Egnor and his ilk - this is why evolution is important to medicine. Such multi- and extensively drug-resistant are predictable because of our understanding of evolution. This allows us to ensure that this sort of things are avoided, and shows us how to deal with it, when it happens.



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