(AP) -- More money and better science are urgently needed to rein in new strains of tuberculosis that are tough or nearly impossible to treat, the WHO announced Monday in China, where the disease has long been a leading killer.

The World Health Organization is releasing its annual update on on Tuesday, which is also World TB Day, an event meant to raise awareness of a disease that despite being one of the world's oldest killers still claims the lives of more than 1.5 million people every year. About 9 million people are infected, most in Africa and Asia.

"Drug-resistant tuberculosis is a growing global public health threat. We are at a turning point. We need to address it," Dr. Cornelia Hennig, the WHO's TB program coordinator for , said at a news briefing in Beijing.

The report comes a week before the start of an international conference in Beijing focusing on ways to deal with drug-resistant TB strains. , China and Russia - the three countries with the world's highest number of drug-resistant TB cases - will participate.

Hennig said the spread of drug-resistant TB strains can be prevented by spending more on TB control programs and coming up with better medical tests and drugs.

Drug-resistance develops when patients are not treated properly or interrupt their treatment after they start feeling better, giving bacteria an opportunity to develop a defense against the medicines.

Multidrug-resistant TB, or MDR-TB, doesn't respond to at least two of the best anti-TB drugs. Extensively drug-resistant TB, known as XDR-TB, is virtually untreatable by remaining options.

"Our treatment options are very, very restricted. ... We almost have no weapon to treat XDR-TB," Hennig said. "Recognition that XDR is a threat is becoming more and more the message."

In 2007, there were an estimated 511,000 cases of multidrug-resistant TB in the world, resulting in more than 130,000 deaths, Hennig said, while about 30,000 people likely died from extensively out of 50,000 cases.

In China, tuberculosis was the deadliest infectious disease for many years until last year, when AIDS became the top killer for the first time.

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