In what is being perceived as a significant breakthrough in the fight against TB, Bikul Das, an Indian researcher at Stanford University has discovered why it is difficult to completely eliminate the TB bacteria even after rigorous treatment.

In a study published in the journal, Science Translational Medicine, Das, who has been researching the subject for the past 15 years, points out that TB bacteria hide in a group of stem cells inside the bone marrow beyond the reach of antibiotics and the body's own immune system. These, he says, reappear once the coast is clear and do a lot of damage. Deepjyoti Kalita, a professor of microbiology with Gauhati Medical College and co–author of the study, calls it a landmark find. "We never knew where TB bacteria used to hide; but now that we know that the bacteria invade and hide in stem cells in the bone marrow, it would be possible to hunt them down and kill them in future. The present medicines don’t help much in this respect."

TB kills 1.9 million people across the globe annually. At present, the most popular treatment for the disease in India is the DOTS regimen, which takes six months to ameliorate the symptoms. But it fails to completely wipe it out. In his research, Das and his team studied the Idu–Mishimi community of Arunachal Pradesh that has a very high occurrence of TB. The team not only found genetic material from bacteria inside the stem cells, they were also able to isolate active bacteria from the cells from TB patients who had undergone extensive treatment. They say the findings indicate that other infectious agents may also employ similartactics.

"We now need to learn how the bacteria find and infect this tiny population of stem cells, and what triggers it to reactivate years after successful treatment of the disease," says Das.