Tuberculosis, an ancient disease, kills 1.7 million people each year, almost all in the developing world. According to the Cambodian Ministry of Health's 2007 report, only three percent of Cambodia's TB patients die following treatment, while 90 percent recover. And health experts say the death toll is likely to grow because new drug-resistant strains have emerged.

Journalist James Nachtwey photographed people with tuberculosis in Cambodia, South Africa and other countries for this slideshow being displayed around the world. Health experts say tuberculosis (or TB) ispreventable and usually treatable.

It kills one person every 20 seconds. Nachtwey's pictures are being distributed by a coalition called ACTION (for Advocacy to Control TB Internationally). Joanne Carter of ACTION in Washington says because of decades of neglect, TB has now developed into newer, deadlier strains. Some are extremely drug-resistant.

JOANNE CARTER: "Even though this disease kills nearly two million people every year, is the biggest killer of people with AIDS, there [are] half a million cases of drug-resistant TB estimated -- new cases -- every year. This issue is receiving very little attention and the hope is that these photographs could actually bring a much higher level of attention to tuberculosis."

Tuberculosis can be treated with powerful drugs, but many poor countries lack the means to detect the disease. Carter says the newest TB drug is 40 years old, there is no effective vaccine for adults, and diagnosing the newer strains is more difficult.

JOANNE CARTER: "In most of the developing world, the diagnostic test that we're using for TB is over a hundred years old, and so while it can detect standard TB, it actually can't detect drug resistance, it has more difficulty detecting TB in people who are HIV positive."

In countries with a poor medical infrastructure, experts say it is difficult to make sure patients continue taking their medications for the minimum six months. Rachel Nugent is with the Center for Global Development in Washington.

RACHEL NUGENT: "Many people who are diagnosed don't get the treatment or don't stay on the treatment. It can take two years to treat them, so it's very difficult to have expectations that somebody in a poor country with pretty bad health facilities is going to be able to continue treatment for a two-year period, and that means that they're going to die."

To view more of Nachtwey's photos and find out about the disease, visit www.xdrtb.org.