They show no symptoms. They’re not contagious. But one-third of the world’s population (according to World Health Organization estimates) carries the latent form of tuberculosis—meaning they can develop the active form at any time. These walking TB reservoirs are the main obstacle to eradicating the disease.
The current treatment for latent tuberculosis lasts nine months and causes many unwanted side effects. But a team of researchers from the Research Institute of the McGill University Health Centre has received the largest grant ever awarded by the Canadian Institutes of Health Research for a clinical trial of latent TB therapy. Principal investigator Dr. Dick Menzies, director of Respiratory Medicine at the MUHC, together with Dr. Kevin Schwartzman, Dr. Andrea Benedetti and Dr. Madhukar Pai from the Montreal Chest Institute of the MUHC, will use the $4.9 million for an international clinical trial to study the effectiveness of a drug called rifampin, currently prescribed for the active form of TB. In order to obtain statistically significant results that can be generalized to a very broad population, the project will involve almost 6,000 patients for 28 months. The study will be directed and coordinated from Montreal, but will also be conducted in centres across Canada, Saudi Arabia, Brazil, Korea, Australia, Benin and Guinea. A rifampin regimen lasts only four months, and the researchers have already shown that it causes a lot fewer side effects; if rifampin also proves as effective as the current latent TB treatment, it will be a much more patient-friendly option for vulnerable and poor populations—and a better tool for fighting this tenacious disease.