TB, substance abuse closely linked in U.S.: CDC

WASHINGTON (Reuters) - About a fifth of people with tuberculosis in the United States report abusing drugs or alcohol, and the figure is even higher when only U.S.-born patients are included, government researchers said on Monday.

The substance abusers were more contagious than others with the disease and remained contagious longer, the U.S. Centers for Disease Control and Prevention researchers wrote in the journal Archives of Internal Medicine.

About a third of people worldwide are infected with the bacterium that causes TB. Only a small percentage of people ever develop the disease. But the effect of substance abuse on the body may raise the chances that the latent infection turns into active disease, and substance abusers may be less likely to be screened for TB, the researchers said.

The researchers tracked 153,268 people with TB in the United States from 1997 to 2006, accounting for nearly everyone age 15 and older with the disease during that span.

Overall, 19 percent of them reported that they abused drugs and/or alcohol, according to the study. Among the 76,816 U.S.-born people with TB, 29 percent reported substance abuse.

The United States has very low rates of TB compared to many other parts of the world, and about half of the people with TB were born elsewhere.

"The most commonly reported risk factor for TB was substance abuse," CDC epidemiologist Eric Pevzner, one of the researchers, said in a telephone interview.

It was greater than are other leading risk factors such as HIV infection or homelessness, the researchers said.

TB is an infectious bacterial disease typically attacking the lungs. It can be spread by breathing in droplets from a cough or sneeze of an infected person.

Pevzner said the findings had important public health implications as the United States attempts to lower its TB rates even further, Pevzner said.

"We can't treat the TB in isolation," Pevzner said. "We have to bring in people who are experts in substance abuse and also treat the life circumstances that people are facing so that we can help cure this disease and help end a chain of transmission."

Substance abusers are less likely to complete TB treatment, the researchers said. They also may have TB diagnosed later and have less access to routine medical care.

(Editing by Maggie Fox and Eric Walsh)