The director of the World Health Organization says drug-resistant strains of tuberculosis are poised to "spiral out of control."
WHO director Margaret Chan says out of more than nine million people who are infected with tuberculosis every year, more than half a million contract a drug-resistant variety.
"This is the true alarm bell," she said. "This tells us that resistant strains are now circulating in the general population, spreading widely and largely silently in a growing pool of latent infection."
Last year's rates of drug-resistant tuberculosis were the highest ever recorded. Yet the World Health Organization estimates less than five percent of drug-resistant TB cases are detected, and fewer than three percent are treated.
The disease is particularly widespread in countries such as China, Russia and Brazil, where health-care systems may be stretched too thinly, and in South Africa, where tuberculosis is found among many of the country's AIDS victims.
In addition, 55 countries have reported at least one case of extensively drug-resistant tuberculosis. That strain is virtually untreatable.
China is second only to India in terms of drug-resistant infections, with 112,000 cases in 2007. In China, 4.5 million people have tuberculosis, and more than 200,000 a year die from the illness.
Health officials from 27 countries, most of them nations with high TB case loads, are meeting in Beijing this week to seek ways to fight the disease. Chinese efforts got a boost Wednesday, when philanthropist Bill Gates announced a $33-million partnership between the Bill & Melinda Gates Foundation and China to diagnose and treat tuberculosis.
Gates says that developing countries are crucial in the fight against tuberculosis.
"As we look ahead to the next decade, the leading indicators in the global fight against TB will be the actions of the world's emerging economies all represented here," he said.
Nearly two million people worldwide die from tuberculosis each year. Infected people can spread the bacteria simply through coughing or sneezing.
Tuberculosis can be treated in half a year, but the drug-resistant form takes up to two years to fight and costs 200 times more to treat.