Researchers hail new treatment for latent TB

LOS ANGELES – In what is being hailed as the biggest breakthrough since the 1960s in treatment for latent tuberculosis – uninfectious TB without symptoms – researchers said Monday that weekly doses of a cocktail of antibiotics can cure the infection in only three months as effectively as the standard treatment of daily drugs for nine months.

By reducing the number of pills and shortening the time required for therapy, the new regimen increased the proportion of patients who completed treatment from 69 percent to 82 percent. By increasing the success rate of therapy, the regimen should reduce spread of the disease and the risk of inducing resistance to TB drugs, experts said.

“It’s very clear that, in this country, if we are going to get rid of TB, we have to do so by preventing people at risk from going on to develop the disease,” said Dr. Richard Chaisson of the Johns Hopkins University School of Medicine, the senior author of the new study. That can only be accomplished by curing latent TB, he said.

Latent TB refers to people who are infected by the TB bacterium, but who do not have symptoms and cannot infect others. But that latent infection can be converted into an active one by many different factors – at which point the patient becomes infectious.

“The 11 million Americans with latent TB represent a ticking time bomb,” Dr. Kenneth Castro, director of the Centers for Disease Control and Prevention’s division of tuberculosis elimination, said at a news conference Monday. “They’re the source of future TB cases.”

Daily doses of the antibiotic isoniazid have been the standard of care for TB for nearly 60 years. But a newer, more potent drug, rifapentine, marketed under the brand name Priftin by Sanofi-Aventis, persists in the body for long periods.

One complication is that the treatment cannot be given simultaneously with drugs for HIV infections, a significant drawback because many patients in the developing world have both diseases.

The trial was sponsored by the Centers for Disease Control and Prevention.