Lung Disease & Respiratory Health Center

Tuberculosis Spreading in Surprising Ways

Oct. 2, 2000 -- Although the ill no longer rest in sanatoriums in the countryside, tuberculosis -- TB -- remains a threat in the U.S. and much of the world. And researchers now report that the bacterium that causes up to two million deaths a year worldwide is proving very, very resilient indeed.

Writing in the Oct. 5 issue of the Journal of the American Medical Association, scientists and physicians from the CDC and the state of Washington also chronicle a search for the source of a TB outbreak that is worthy of a detective novel.

With the aid of DNA testing on the bacteria itself, which identifies the bacteria somewhat like a fingerprint, they determined that a man sickened with TB contracted it through contact with a laboratory test of another person with TB who lived more than 60 miles away. The two had never met, but the one man worked in a medical waste treatment facility that processed old TB tests after they were discarded. The infection occurred despite the fact that the bacteria was subject to steaming, shredding, compacting, and another process that was supposed to deactivate it.

This is the first documented case of TB being transmitted through medical waste. Typically, TB is transmitted from an infected person through coughing or other means in which the bacteria becomes airborne and is breathed in by another person. More unusual methods of transmission have been reported, including a case of a funeral worker contracting TB from a dead body. And in 1995, scientists in Arkansas reported that personnel performing an autopsy on someone who died of TB developed the disease themselves -- even though the health care workers who cared for the person showed no signs of TB.

"The message is we can't let our guard down," Kammy R. Johnson, DVM, PhD, tells WebMD. "TB doesn't go away when it is asked. It is still causing significant illness and death. We can't turn our backs on this disease." Johnson, a senior health research scientist at the CDC in Atlanta and the lead author of the article, adds that more attention must be given to ways people may catch TB through their jobs.

The U.S. has a national TB elimination program and every state has officials charged with monitoring and controlling any outbreaks. TB was once thought to be nearly eradicated here, but there was a significant resurgence of the disease from 1985 to 1992, when the number of cases grew by 20%. Progress has been made, however. In 1953, there were 85,000 new cases of TB, compared to 17,000 in 1999. At the same time, more cases are being discovered that are resistant to drugs, which makes the disease more difficult to do away with.