Preventive treatment for tuberculosis (TB) can stop latent TB infections (with no symptoms) from developing into deadly diseases later.

Notably, researchers from Boston University in the US found that preventive TB treatment was not effective in most individuals who did not show evidence of infection, except for children under 5.

Among 439,644 participants, the team found that preventive TB treatment was 49 per cent effective among the 2,496 individuals who developed TB, but particularly among individuals with a positive skin or blood test (for which the effectiveness was 80 per cent).

“While it is critical to find and treat people who are spreading TB in the community, the threat of global TB will never end until people with latent TB receive treatment. The results of this study show just how effective such treatment can be,” said Dr. C. Robert Horsburgh, professor of global health at the varsity’s School of Public Health.

“Tuberculosis affects tens of millions of people every year and has long-term lasting effects, even after people recover. Finding ways to optimise prevention is really important to tackle the epidemic," said lead author Dr. Leonardo Martinez, assistant professor of epidemiology.

The team also estimated the number of needed-to-treat (NNT) to prevent one person from developing TB disease.

Regardless of infection status, the NNT was lower in high-burden settings (29 to 43 people) versus low-burden settings (213 to 455 people), the study showed.

“Despite the fact that individuals with negative blood or skin tests do not seem to benefit from preventive treatments, the researchers say the overall low NNT may justify prioritising this treatment to all exposed contacts in areas where testing for TB infection is inaccessible,” the team said.