Two new studies show drug resistant tuberculosis germs can become a major public health threat more easily than previously thought. More than 275,000 new cases of multi-drug resistant TB were reported in 2000, in more than 100 countries.
The two mathematical modeling studies in the journal Nature Medicine show weaker, but drug-resistant strains of TB taking over in many places after TB treatment programs knock stronger, but drug-sensitive strains out of the population. One study showed that some areas with better TB control programs were paradoxically more likely to become "hot zones" with high rates of multi-drug resistant TB than places with poor programs.
The World Health Organization aims to improve TB control programs worldwide with a strategy called "DOTS," for directly observed therapy. Sally Blower at the University of California Los Angeles medical school co-authored one study. She says DOTS is still the best strategy to use in most places.
"Certain regions, and by far the majority, would do very well with DOTS," she said. "But there are certain other regions, the minority, that are very crucial, and that need to be treated in a very different way. And they are connected globally so that we should be concentrated right at this moment, and not waiting for the future, to deal with the hot zones."
The studies say second-line drugs need to be introduced in those hot zones, even though they are more expensive, because costs will be higher still if multi-drug resistant tuberculosis ever takes hold.