Nipping TB in the bud

According to the World Health Organization, tuberculosis is the leading cause of death by infectious disease worldwide. One quarter of the world’s population is infected with latent TB, a condition in which the bacterium lies dormant in the body without being infectious or causing symptoms. Some people with latent TB, such as those with compromised immune systems, are more susceptible to its activation than others. Treatment is prescribed in these cases as a preventative measure. But, patient adherence to a prolonged treatment programme is often a problem.

Researchers compared the standard nine-month isoniazid regimen used to treat latent TB in the US and Canada with a shorter four-month plan using rifampin in 6,900 patients in several countries worldwide, including Saudi Arabia.

The study showed that the probability of developing active TB fell within a month of starting either treatment, says Dick Menzies, of the McGill International TB Centre in Canada. But prematurely ending treatment increased the probability once more. Monitoring patient intake showed that treatment completion was 15% higher among patients prescribed with the four-month rifampin regimen. They also experienced fewer side effects.

Based on the study’s results, the standard nine-month treatment of latent TB with isoniazid should be replaced with the shorter four-month treatment with rifampin, says Menzies. 

Ziad Memish, senior infectious diseases consultant at Prince Mohammed Bin Abdulaziz Hospital in Saudi Arabia, says latent TB is very common in the Middle East as a result of a large number of expatriates arriving from TB-endemic countries. 

We needed more robust data to show the clinical equivalence of using rifampin alone for a shorter duration to treat latent TB compared to longer regimens, says Memish, who was not involved in the study. “The strength of this new report is its very large sample size representing an international mix of patients with good follow-up for 28 months.”

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