Tuberculosis is the number one killer of women of childbearing age worldwide, and the epidemic is growing with the spread of drug-resistant bacteria. Experts attending the 4th World Congress on Tuberculosis in June said that latent TB is a difficult disease to diagnose. In poor countries, women with the disease often aren't diagnosed until severe symptoms appear, they said.

"Many women are diagnosed only after they have become too ill" to care for their families, said Carol Nacy, head of the Sequella Foundation, a group organizing tests for new TB drugs and vaccines. By the time the disease is diagnosed, a patient may have infected 10 to 15 others, Nacy said. Even when women are diagnosed and receive TB drugs, mothers will often give the medicine to their children instead of taking it themselves. "That's one reason TB is the number one killer of women of childbearing age," Nacy said.

About one-third of the human population -- roughly 2 billion people -- are infected with TB, often in a latent form. But even in that form, the disease can be spread as droplets from sneezing or coughing. About 10 percent of those with a latent infection, some 200 million people, will develop active disease. About 2 million people worldwide die of TB annually, and some estimate that more than 90 million people could succumb to the disease over the next 30 years.

TB is a significant public health problem in developing nations, with China and India accounting for about one-third of all cases worldwide. There were fewer than 16,000 cases of active TB in the United States last year, about half involving recent immigrants.

A combination of drugs, including isoniazid and rifampin, has been shown to cure TB, but medications must be taken every day for six to nine months. Failure to take the full course of drugs encourages the development of drug-resistant strains of TB, which can then be passed from patient to patient. Drug-resistant TB represents about 14 percent of the cases in Estonia and more than 10 percent of those in one province of China. Worldwide, experts estimate that about 4 percent of TB cases involve a bacterium resistant to at least one of the drugs. A report by the US National Institute of Allergy and Infectious Diseases said an outbreak of drug-resistant TB a decade ago in New York City cost almost $1 billion to control. The CDC said drug-resistant cases of TB have dropped in the United States from 2.7 percent of all cases in 1993 to about 1.2 percent.

The World Health Organization, the National Institutes of Health, the CDC, foundations such as Sequella, and health agencies in many countries are working to control TB through development of new drugs and vaccines, aggressively pushing programs of treatment, and finding new ways to diagnose the disease quickly while it is in its latent form. New cases of TB have declined in countries, including India and China, using directly observed treatment short-course (DOTS), using health care workers to confirm that TB patients take their medications. DOTS is now being used in 148 countries, said Dr. Jong-Wook Lee, head of WHO's TB program. WHO's goal is to identify 70 percent of new TB cases and to cure 85 percent of them, Lee said. "Even in huge countries with a heavy burden of TB it is possible... to achieve very high levels of cure," Lee said.

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