'Just breathing, and not necessarily coughing, enough to spread TB' — study

It has long been assumed tuberculosis (TB) is spread through coughing and that practising cough etiquette may reduce chances of transmitting TB germs, but new findings have shown normal breathing may be a major contributor to the spread of the disease. 

Researchers at the University of Cape Town (UCT) say given a large number of normal breaths every individual takes in a day, breathing alone is estimated to contribute more than 90% of the daily TB bioaerosol (airborne collection of biological material) output among patients with active TB disease. 

Aiming to advance understanding of how TB is aerolised, PhD graduate Ryan Dinkele developed a novel method for the microscopic detection of the TB germ in bioaerosol samples. He collected bioaerosol samples from 30 TB patients using a respiratory aerosol sampling chamber — a custom-made personal clean room built to catch bioaerosols or the droplets that become aerosolised. 

“I found that the sensitivity of this method was high, about 90%, which was striking as the participants were sampled for 60 minutes without any requirement for forced coughing,” said Dinkele.  

This observation led to the second component of his work, which is testing the long-standing assumption that coughing is the primary driver of TB transmission. For this, Dinkele altered the sampling chamber to allow for the direct comparison of breathing, deep breathing, and coughing. 

TB detection methodology was then applied to independently examine the bioaerosols from each of the samples. “This work forces us to challenge long-standing assumptions that are currently accepted in TB research,” said Dinkele who graduated this week with a PhD in medical microbiology. 

“Prior to the Covid-19 pandemic, TB was the leading cause of death owing to a signal infectious agent, globally. Unlike Covid-19, however, TB remains out of the global spotlight, predominantly impacts young adults, and disproportionately affects the poor. The inability of antibiotics and the TB vaccine to eradicate the epidemic necessitates further research into how, when, and by whom, TB is spread.” 

Meanwhile UCT’s drug discovery and development centre, H3D, has announced a new partnership in which the South African Medical Research Council (SAMRC) will award a grant to the University of Venda’s chemistry department to boost local TB research.  

The R2.4m grant over the next three years will support a project titled “TB drug discovery capacity development project”. 

A similar partnership which is aimed to increase support for historically disadvantaged institutions was entered into with the University of Limpopo last year. 

SAMRC president and CEO Prof Glenda Gray said it’s crucial to take a proactive approach to co-ordinate health innovation in South Africa. 

“We need to bolster South African science's abilities to research and develop novel or enhanced drugs, vaccines, diagnostics, and medical devices for the priority diseases. By partnering with local universities, science councils, and the private sector, we can enhance the transfer of research findings into improved health results and social advantages.”

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