Researchers from the Centers for Disease Control and Prevention (CDC) have found that roughly one in five people with tuberculosis (TB) in the U.S. reported abusing alcohol or other drugs, making addiction the leading risk factor for the disease, Reuters Health reported Jan. 27.

The researchers studied nearly all U.S. residents ages 15 years and older who had TB between 1997 to 2006 and found that 19 percent of those infected — and 29 percent of those born in the U.S. — reported abusing alcohol or other drugs. Those with addiction problems were more contagious than those not using drugs, and TB remained contagious for a longer period of time among those using drugs.

Substance abusers also may be less likely to be screened for TB or complete treatment, and may be diagnosed with the disease later, the study authors added.

Researchers said addiction was a greater risk factor for TB than HIV infection or homelessness.

“We can’t treat the TB in isolation,” researcher Eric 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.”

The study was published in the Jan. 26, 2009 issue of the Archives of Internal Medicine.