US study finds way to prevent TB

2011-05-16 18:29

New York - US health officials say they have found a far simpler therapy for people at risk of developing tuberculosis, addressing a key barrier to preventing the spread of the disease.

Patients who took a combination of two drugs just 12 times over three months fared as well as those who received the standard treatment that requires 270 daily doses, according to a landmark US government study released on Monday.

"New, simpler ways to prevent TB disease are urgently needed, and this breakthrough represents one of the biggest developments in TB treatment in decades," Thomas Frieden, director of the US Centres for Disease Control and Prevention, said in a statement.

The far less onerous regimen involves taking rifapentine, an antibiotic sold by French drugmaker Sanofi under the brand name Priftin, along with isoniazid, an effective tuberculosis drug in use since the 1950s.

The study results, presented at a medical meeting on Monday, could mark a major advance in preventing TB in countries with low-to-medium incidence of the highly infectious disease, according to the CDC, which sponsored the study.

While many people believe TB to be a largely conquered disease of the past, there were more than 11 000 cases reported in the United States last year, and it remains one of the world's leading infectious killers, according to the CDC.

The 10-year study included more than 8 000 patients with latent TB infection, meaning they have the tuberculosis bacteria in their bodies but no symptoms and are not contagious.

More than 11 million Americans are positive for latent TB, the CDC said, with Asians, other minorities and foreign-born individuals disproportionately affected.

Highest incidence in history

Between five percent and 10% of people with latent TB develop the disease. Those with a weakened immune system are particularly susceptible.

While the results mark a significant finding for fighting TB in countries like the United States, researchers stressed the need for additional studies before the new regimen can be recommended in countries with a high incidence of the disease, especially those with high HIV prevalence, due to a known drug interaction between some anti-HIV drugs and rifapentine.

Worldwide, TB kills an estimated 1.7 million people each year, and the number of new cases - around 9.4 million - is higher than at any other time in history, according to the World Health Organisation.

In the US study, patients with latent TB received either 900mg each of rifapentine and isoniazid once a week for 12 weeks under a doctor's supervision, or the current self-administered standard of 900mg isoniazid every day for nine months for a total of 270 doses.

The combination therapy was found to be safe and as effective as the standard regimen in preventing new cases of TB disease, according to researchers who presented the data at the American Thoracic Society International Conference in Denver.

Seven cases of TB occurred among those receiving the new treatment regimen, compared with 15 cases among those on the lengthy standard treatment, researchers said.

While the old one-drug method works, patient compliance has traditionally been a problem.

"Ensuring that those who need treatment both begin and complete the lengthy, cumbersome isoniazid regimen is challenging," Frieden said.

In the CDC study, 82% completed the new, shorter regimen, compared with a 69% completion rate for the standard nine-month regimen.

"By effectively treating latent TB infection, not only can we reduce the potentially deadly consequences among those individuals, but we can also prevent many others from ever becoming infected," Kevin Fenton, director of CDC's National Centre for HIV/Aids, Viral Hepatitis, STD, and TB Prevention, said in a statement.

Given the promising results and potential for far higher patient compliance under the new regimen, CDC said it had begun working on new guidelines for its use in the United States.

- Reuters