On October 30th, Professor Robin Wood, co-founder and former CEO of the Desmond Tutu Health Foundation (DTHF), took the stage at the DTHF Science and Community event to present his latest insights into tuberculosis (TB) research. The plenary, titled “Hunting Bosons,” explored the hidden reservoirs of TB transmission and the paradigm shifts reshaping our understanding of this persistent epidemic.
A Paradigm Shift in TB Control
For over a century, TB control efforts have focused on diagnosing and treating symptomatic cases, but Professor Wood emphasized that this traditional approach might be insufficient. “I think we are changing the paradigm of tuberculosis,” he stated, noting that research now targets hidden reservoirs of TB transmission beyond visible, symptomatic cases. This shift aims to explore how TB silently spreads within communities through carriers who exhibit no symptoms yet contribute to transmission—a phenomenon he described as the “bummock,” an unseen population likened to the hidden bulk of an iceberg.
Challenges and Unseen Carriers
Cape Town’s high TB transmission rates highlight the limitations of conventional TB control measures, rigorously implemented for decades. “Cape Town introduced compulsory notification of TB eight years before the United Kingdom,” said Professor Wood. “We’ve been trying very hard for 100 years.” Unlike cities such as London and New York, which managed to reduce TB rates even before effective therapies were available, Cape Town’s TB burden remains substantial, suggesting that socioeconomic and environmental factors may also play a critical role in TB control.
New research sheds light on the idea that asymptomatic carriers—individuals who carry the bacteria in their exhaled breath without showing symptoms—may unknowingly spread TB within communities. “We think we might have discovered the bummock,” Wood explained. “A hidden population of potential transmitters that may constitute an unrecognized reservoir of TB.” These findings point toward a paradigm shift that may reshape global TB control strategies, placing emphasis on identifying and addressing asymptomatic transmission.
Innovations in TB Detection
To detect these hidden carriers, researchers have turned to advanced diagnostic tools capable of capturing and analyzing TB bacilli in exhaled breath. Professor Wood highlighted innovations such as the diesel engine particle counter and a simplified breath condensate collection system. “We developed this system to capture exhaled TB bacteria from breath… and we think this might be the first-ever picture of an exhaled TB bacillus,” he said. These technological advancements hold promise for more accurately identifying TB carriers who may otherwise go unnoticed.
The Role of Immunology and the BCG Vaccine
Professor Wood also emphasized the immune system’s role in controlling TB. Data suggest that immune responses can suppress TB bacteria, even in asymptomatic carriers. “The symptoms we see may be caused by the immune recognition of these TB cells,” he explained, noting that those without symptoms might still carry and spread the bacteria. This insight could pave the way for new vaccines aimed at reducing transmission rather than solely preventing severe disease.
While the BCG vaccine remains vital in protecting young children from severe forms of TB, it has limited impact on transmission rates among older populations. “BCG vaccination at birth helps prevent severe TB in children,” Wood acknowledged, “but does not significantly impact TB rates in older age groups.” The new research on asymptomatic transmission could direct efforts toward more effective immunization strategies that target these hidden reservoirs.
Socioeconomic Determinants and Public Health Implications
Looking at historical data, Professor Wood pointed out that improved living conditions and nutrition likely played a major role in reducing TB rates in New York and London before effective medical treatments were available. “Did the West get rid of the organism, or did they just change the host?” he asked, highlighting the impact of better overall nutrition. In these cities, TB gradually became a disease affecting older adults, signaling that socioeconomic improvements likely interfered with TB transmission.
These insights carry major public health implications. If asymptomatic carriers can be identified and targeted with specific vaccines or treatments, TB transmission could be better controlled within communities. “If we can identify asymptomatic carriers, we may be able to target them with vaccines or treatments, effectively controlling transmission,” Wood said, calling for a re-evaluation of TB strategies that prioritize both medical and social interventions.
The research presented by Professor Wood at the Science and Community event underscores the importance of adapting TB control strategies to address hidden sources of transmission. As he concluded, the lessons learned from TB control efforts in the Northern Hemisphere combined with the latest technological advances in diagnostics and immunology offer a new way forward—one that could bring us closer to ending TB globally.
Here is the link to the recording of his talk: https://youtu.be/WZoosWU4GyA
