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Shorter drug regimen could help eradicate TB

An international study that included six VA sites found that patients with latent tuberculosis—meaning they are infected with the TB germ but have no symptoms and are not contagious—can keep the disease from developing by taking a combination of drugs once a week for three months. The new drug combo appears to work just as well as the current standard of care, which calls for taking one of the drugs daily for nine months.

The researchers reported the findings in the Dec. 8 New England Journal of Medicine, and the Centers for Disease Control and Prevention, which sponsored the study, has since issued new clinical care guidelines based on the results.

Reflections of history: VA TB trials in the 1940s

After World War II, VA, in conjunction with the Armed Forces, conducted a major study to test the effectiveness of the antibiotic streptomycin to treat tuberculosis. At the time, the potentially fatal disease was a huge public health problem.

The initial results in the hundreds of Veterans who took part were very favorable: The patients' fevers went down, their appetite and weight improved, and their overall sense of well-being improved.

Continued monitoring of the study participants, however, revealed two concerns about the streptomycin: It often caused inner ear damage that affected balance, and many patients developed resistance to the drug.

A follow-up trial in 1947 determined that a lower dose of streptomycin could achieve similar therapeutic results with less toxicity and less risk of drug resistance.


Information adapted from A Historical Look at the Establishment of the Department of Veterans Affairs Research and Development Program by Marguerite T. Hays, MD.

Largely thanks to antibiotics, TB rates in the U.S. have fallen to all-time lows. Last year, there were only about 11,000 reported cases of TB illness. But there are some 11 million Americans with latent TB who "represent a ticking time bomb. They're the source of future TB cases," said Rear Admiral Kenneth Castro, MD, director of the CDC's Division of Tuberculosis Elimination.

Up to 10 percent of those with latent TB will develop the disease if they are not treated, but most don't know they are infected. Of the 300,000 to 400,000 Americans with latent TB who undergo preventive treatment each year, most learn of their infection through screening programs that target high-risk people, such as workers at hospitals, homeless shelters, drug rehab clinics, and prisons; or patients with HIV, diabetes, or head and neck cancers.

Nearly 8,000 high-risk individuals from Brazil, Canada, Spain and the U.S. took part in the study. Of that number, about half received a combination of two drugs, rifapentine and isoniazid, once a week for 12 weeks, in the presence of clinic staff. Isoniazid alone was given to the other participants, who were told to take the drug daily for nine months, on their own at home.

After following patients for up to nearly three years after the medications were given, the researchers found that only seven (0.19 percent) of those who had taken the combination of drugs had developed TB. By contrast, 15 (0.43 percent) of those who had taken isoniazid alone developed the disease. In addition, 82 percent of those on the combination therapy completed the three-month course of treatment, whereas only 69 percent of those who took isoniazid for nine months completed their regimen.

"It's clear that the CDC now expects this [combination therapy] to immediately become the new norm for prevention of TB," said Fred Gordin, MD, chief of infectious diseases at the Washington, DC, VA Medical Center, and one of the study's authors.

Other VA sites participating in the trial were the VA medical centers in Little Rock, Chicago, Hines (Ill.), Houston, and San Antonio.

The study authors pointed out that more research is needed to see if people on the shorter, three-month regimen would take their medication even when not supervised in-person by medical personnel.


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