The World Health Organization warned that drug-resistant tuberculosis is spreading fast with unpredictable results. It has already reached previously unthinkable rates of more than 20 percent in some countries. The highest rate recorded was in Baku, the capital of Azerbaijan, where 22.3 percent of new tuberculosis cases were resistant to the standard anti-tuberculosis drug treatment, WHO says.

"Ten years ago, it would have been unthinkable to see rates like this," said Dr. Mario Raviglione, director of WHO's "Stop TB" department. "This demonstrates what happens when you keep making mistakes in TB treatment."

The new WHO report released Tuesday is based on data from 2002 through 2006. However, only about half of the world's countries were able to provide the required data. For example, only six countries provided information in Africa.

There is also concern about the so-called XDR-TB, or extensively drug-resistant TB, a strain virtually untreatable most times. In the United States, 1.2 percent of TB cases were multi-drug resistant in the 2002-2006 period, and of those, only 1.9 percent were extensively drug-resistant.

Tuberculosis can be relatively easily transmitted from an infected individual to a healthy person in saliva droplets through coughing, sneezing, singing and other activities. The WHO said around $4.8 billion is necessary to fight the disease, especially in low- and middle-income countries which cannot sustain the costs by themselves, with one billion dollars specifically set aside for resistant strains. However, only about the half that funding is currently committed.

"Multi-drug resistant TB is a threat to every person on the planet," said Mark Harrington, executive director of Treatment Action Group, to AP. "It's not like HIV, where you are only infected through specific actions. TB is a threat to every person who takes a train or a plane."

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