90% of symptomatic individuals not diagnosed with TB may also harbor tuberculosis bacteria: Study

Tuberculosis remains a significant global health concern with approximately 10 million people worldwide suffering from it, according to the World Health Organization (WHO). Mycobacterium tuberculosis, the bacterium responsible for tuberculosis (TB), enters the body through inhalation and primarily affects the lungs. Once inhaled, the bacteria can evade the immune system. The bacterium spreads through the air when an infected individual coughs or sneezes, making it highly contagious and can affect other organs besides the lungs, leading to extrapulmonary TB.

“If someone carries Mtb in their respiratory tract, this may also mean they can spread it. Therefore, since these results suggest a much broader range of people transmitting TB than previously recognized, there are significant implications for public health interventions designed to interrupt transmission,” said Ben Patterson, external Ph.D. candidate at Amsterdam UMC and the Amsterdam Institute for Global Health and Development.

In the study, participants were evaluated for TB diagnosis. Aerosol samples were collected in a dedicated TB aerobiology lab. These samples, gathered from all participants, detected Mtb in 90% of patients, even those initially testing negative for tuberculosis via sputum analysis. Sampling was repeated at three intervals over six months for each participant.

Researchers found that the presence of Mtb decreased in those on treatment as well, surprisingly, as those not on treatment over the period. Nevertheless, 20% of participants continued to test positively for Mtb in aerosol after six months. The findings suggested that the transmission could continue over a period longer than previously thought.

"Together, our results indicate how complex tuberculosis is, and perhaps also why it is so difficult to eliminate tuberculosis in endemic areas. Even when public health agencies work, according to the current guidelines, effectively against symptomatic TB cases. In this sense, a revaluation of our practices is necessary,” said Frank Cobelens, professor of Global Health at Amsterdam UMC and senior fellow at the AIGHD.

Reference: Journal: Proceedings of the National Academy of Sciences