May 16 2011
The findings of a large government trial show a treatment regimen that differs from the standard therapy may be effective in treating the latent form of tuberculosis.
About 11 million people in the U.S. are infected with latent tuberculosis, which is symptom-free and is not contagious. Of those, 5 to 10 percent will go on to develop active TB, which can be spread to others and can be fatal if not properly treated.
Researchers looked at 8,000 people with latent TB, mostly in the United States or Canada. They were randomly given one of two treatments- the standard course of therapy, which takes nine months of daily treatment, or a once-weekly treatment for three months. The standard treatment is isoniazid. The experimental regimen combined isoniazid with rifapentine.
"The treatment of latent TB can be shortened from 270 doses to 12 doses, and be just as effective- that's pretty impressive," said Dr. Dean Schraufnagel, president of the American Thoracic Society and a TB expert.
Those on the once-weekly treatment were more likely to complete it- 82% versus the current rate of 69%.
"This new treatment for TB may have great, extraordinary consequences," Schraufnagel said. "I believe this will be a major strategy to control TB, both in the U.S. and worldwide."
Statistics from the CDC show the case count is on the decline, but in 2007, 544 deaths occurred from TB. In 2009, the case numbers were at an all-time low. Asians, African Americans and Native Hawaiians, along with foreign-born individuals, are disproportionately affected more than whites.
“Achieving CDC's goal of TB elimination in the United States means not only treating those individuals who already have TB disease, but also treating those with latent TB infection who are at high risk of developing TB disease and potentially transmitting it to others,” said Dr. Kevin Fenton, Director of CDC’s National Center for HIV-AIDS, Viral Hepatitis, STD and TB Prevention (NCHHSTP).
“While the number of reported cases of TB disease is currently low, in today's highly interconnected world, we need to guard against a resurgence of TB both at home and abroad,” he added.
Symptoms of TB can include chest pain, a bad cough (possibly with blood), weakness and a fever. While TB usually impacts the lungs, the kidneys, brain and spine may also be affected.
Schraufnagel said people with latent TB who go on to develop active TB won't know it at first.
"They'll develop a little cough- the cough persists," he said. "They think it might be a cold, sometimes they might have a little fever. This cough doesn't go away and after a month or two months, or three months, they may contact a doctor. And even then, they're often treated for a cold or some other thing. Then they would get an X-ray or examine the sputum and make the diagnosis of TB. By that time, those people have infected 10, 20, 30, 40, a lot of new people."
The CDC offers these guidelines as to who should get tested for TB:
- If you've been around someone with active TB disease
- If you have HIV or another condition that makes the immune system weaker
- If you live in a homeless shelter or some nursing homes
- If you are from a country where TB is very common
- If you inject illegal drugs
One-third of the world's total population are infected with TB bacteria, according to the World Health Organization.
It says each person who becomes sick with active TB, if not treated, can infect on average 10 to 15 other people a year.
"It's important to note that the study was conducted in countries which carry a low to medium incidence of tuberculosis,” said Dr. Kenneth Castro, Director, Division of Tuberculosis Elimination, NCHHSTP. "That is primarily in the United States and Canada, and the results can therefore only be applied to these settings. The trial did not include countries with high tuberculosis incidence where the increased risk of re-infection could affect the effectiveness of this regimen."