Researchers Report Breakthrough in Treatment of Latent Tuberculosis

Most Americans grew up with the understanding that tuberculosis was rare in developed countries. However, the incidence of the disease began to rise around 25 years ago. Experts attribute the increased prevalence of the illness in part to HIV and AIDS, which weaken the immune system and make it harder to avoid contracting many conditions. They're excited about a new study conducted by Vanderbilt University scientists that suggests a major breakthrough in the treatment for the more common form of tuberculosis (TB).

What is Latent TB?

According to the Mayo Clinic, when diagnosing tuberculosis, doctors are careful to distinguish between two types of the disease. Patients with active TB are contagious the first few weeks after they're infected with the bacteria that cause tuberculosis.

However, the majority of individuals who become infected never develop active TB. They suffer from latent TB. These individuals can't spread the illness. Bacteria remain in the body but inactive. They cause no symptoms.

Standard TB Treatment

For many years, the standard treatment for latent tuberculosis has been a nine-month regimen of pills taken on a daily basis. The Washington Post reports that a new study, headed by Timothy Sterling, M.D., of Vanderbilt University, showed that a much shorter treatment using drugs patients take just once a week is equally effective and just as safe.

For individuals exposed to patients who have active TB and for those with the latent form of the illness, the standard treatment has been considered the best chance at avoiding the active form of the disease. The regimen prescribed has been a once-a-day dose of the drug isoniazid for a period of nine months.

However, the Vanderbilt study suggests that taking a higher dose of the same medication gives equally safe and effective results if isoniazid is used with the drug rifapentine. Both drugs need to be taken once a week for three months on a supervised basis.

The Study

The Vanderbilt study was one of the largest clinical trials sponsored by the U.S. government on therapy to prevent TB, according to the Centers for Disease Control and Prevention (CDC). This agency funded the study, which followed 8,053 subjects over the age of 2 for a period of 10 years.

The patients resided in the United States, Canada, Spain and Brazil, countries considered to have a low to medium incidence of the disease. Individuals with HIV who were taking antiretrovirals were not permitted in the study because of potential drug interactions.

One of the most dramatic findings involved the rate of completion of the treatment. While 69 percent of patients following the standard protocol stuck with their treatment to completion, 82 percent of those on the shorter regimen finished it. However, the shorter course of treatment cost $503 per patient as opposed to $237 for the standard protocol.

Impact

Because of the positive outcome of the Vanderbilt study, the CDC has asked experts to go over the data and develop guidelines to use the results. Since the study focused only on countries where the incidence of TB is considered low to medium, before the shortened treatment can be utilized in other areas, further studies will be required.

An additional concern is how the results might apply in areas with a greater-than-average incidence of TB re-infection and those where AIDS and HIV are considered prevalent.

Within the U.S., around 11 million individuals have latent tuberculosis. In 2010, slightly more than 11,000 developed active TB. Experts hope the breakthrough will make life easier for the 300,000 Americans who undergo treatment for latent TB each year and will cut the number who develop active tuberculosis.

Sources:

http://www.mayoclinic.com/health/tuberculosis/DS00372/DSECTION=symptoms

http://www.washingtonpost.com/national/health/new-study-dramatically-cuts-treatment-for-latent-tb/2011/05/16/AFLQvE5G_story.html

http://www.cdc.gov/nchhstp/newsroom/PREVENTTBPressRelease.html