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Tuberculosis Remains a Global Threat


Saturday, 24 March 2007, is World Tuberculosis Day. It is also the 125th anniversary of the discovery of the bacterium that causes the lung disease.

But many experts say humankind has not advanced much in combating the disease since that discovery, using containment tools that are almost as old. The most commonly used TB drug appeared more than 30 years ago, yet the emergence of hard-to-treat, drug resistant forms is outdating the medicines.

The face of tuberculosis is an old face. But it is also a young face. It is an African face, an Asian face, a Middle Eastern face -- the face of anyone, anywhere. But for all, it hurts to breathe. The TB bacterium is eating their lungs.

The World Health Organization says about nine million people around the world have TB and 1.6 million die from it every year. The greatest burden is in South and East Asia, followed closely by Africa and the Western Pacific regions, all adding up to 85 percent of the world total.

To the director of the WHO's Stop-TB Program, Mario Raviglione, the deaths are needless, because a six month course of drugs that have been around for decades can cure most cases of TB. "It is a scandal that in 2007, with the means we have, we could potentially cure all drug-susceptible cases of TB," says Raviglione, "[but] we still see 4,500 deaths every day. So the world must wake up."

Obstacles and Super Strains

TB persists, and mutates into drug-resistant strains harder to cure, because many patients fail to finish taking their medicine. The chief of TB research at the U.S. government's National Institute of Allergy and Infectious Diseases, Dr. Clifton Barry, says it is a lengthy regimen. "That's very, very difficult to do, just logistically keeping patients taking medicine for six months," notes Dr. Barry. "It's not a solution that works in the developing world, where the local district health center might be 50 kilometers away and your only access to it is by walking."

For years, the World Health Organization has promoted directly observed therapy by local health care workers who go to patients' homes to make sure they take their pills. But in poor countries with weak health systems, health workers to do this are in short supply. As a result, bacterial resistance to at least two common TB drugs is spreading, requiring newer, more expensive and more toxic compounds to do the job.

"We know it's out there, but we don't know how much of it is out there," says Joann Carter, of the non-governmental group RESULTS, which helps fund medical projects in developing countries. She notes that an even more dangerous TB strain has developed recently. The bacterium has mutated further into a form resistant to most of the older and newer drugs. This so-called extremely drug resistant strain, or XDR tuberculosis, was first noticed in South Africa, fueled by the HIV epidemic that weakens patients' ability to fight such diseases.

Carter calls it a scary superbug that kills 70 to 80 percent of those infected and threatens to reverse progress in treating AIDS. "What you've seen in parts of the world with high rates of HIV is that that drives up TB rates enormously. So when you put together multi-drug resistant TB or extremely drug resistant TB with HIV, it's really a potential explosion of a very deadly disease," she warns.

Other Disease Threats

HIV is not the only disease that lets TB thrive. Diabetes also invites it, a worrisome connection because diabetes incidence is growing rapidly worldwide as a side effect of the global obesity epidemic. Studies show that people with adult onset diabetes may be six times more likely to get TB than those without it.

The Director of the Johns Hopkins University Center for TB Research in Baltimore, Dr. Richard Chaisson, says it could be because diabetes, like HIV, weakens today body's natural immunity to disease. "Blood sugar levels that we see in diabetes impair the immune system and allow the tuberculosis organisms to get the upper hand," says Chaisson. "So we need to target our TB screening and TB prevention programs at people with diabetes, and thus far very little has been done about that."

The XDR strain of tuberculosis is thought to account for a small portion of the global TB burden. But Mario Raviglione at the World Health Organization warns that it could spread without strengthened health and surveillance programs in poor countries, more rapid diagnostic tools and better, speedier drugs.

Winning the Battle

Raviglione notes that controlling XDR TB will require an extra $650 million a year from the global community in addition to what it is already spending. "XDR TB is probably the worst thing that one would ever have imagined," he says. "I've been working now in TB control for the last 15-16 years, and I can tell you that this is by far the biggest scare we have ever faced."

Lung specialist Lee Reichman of the New Jersey Medical School's National Tuberculosis Center argues that new drugs and diagnostic tools will fail if poor countries' health systems are not bolstered to deliver them efficiently. But Reichman says XDR TB is curable with political will and novel thinking. "You have to be ready to think of new things in tuberculosis because what we're doing so far hasn't worked that well," warns Reichman.

This story was first broadcast on the English news program, VOA News Now. For other Focus reports click here.

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