There are millions of people across the world who are ‘silent spreaders’ of tuberculosis – and researchers have taken a step closer to identifying who they are.
A study led by researchers from the NIHR Southampton Biomedical Research Centre (BRC) has identified a group of biological markers that are found in high levels among infectious patients. They hope the findings will pave the way for a simple test to speed up the diagnosis of tuberculosis (TB).
This could help stop the spread of the infection, which affects an estimated 10 million people around the world each year. The study was supported by the National Institute for Health and Care Research (NIHR) and the Medical Research Council, and was published in the Journal of Clinical Investigation Insight.
TB is the world’s deadliest infectious disease. It is estimated to kill more than one million people each year, according to the World Health Organization.
Researchers from the Southampton BRC carried out the most detailed analysis ever undertaken of blood markers for the bacterial infection. The team used a novel technique to identify a set of six proteins that are highly accurate in pinpointing TB.
Lead author Dr Hannah Schiff, an NIHR clinical lecturer at the University of Southampton, said as many as three million cases were missed last year. Most of the undiagnosed cases were in developing countries.
“TB remains a global catastrophe. Our efforts to control the spread are hindered by inadequate testing, which is slow and reliant on specialist equipment and labs,” she said.
“A third of people who get infected go undiagnosed and remain infectious. In our study, we combined a new measurement technique with deep mathematical analysis to identify these six new markers of TB disease.
“It could lead to a transformative alternative to diagnosing the condition – a simple test that detects proteins in the bloodstream whose levels differ between people with TB, healthy individuals, and those suffering from other respiratory illnesses.”
While TB mostly affects the lungs, it can devastate any part of the body. Cases in the UK increased to around 5,000 last year. They are expected to continue rising in 2024, according to the UK Health Security Agency (UKHSA).
The study was undertaken with academics from the University of Cape Town in South Africa and Cayetano Heredia University in Peru. The research team studied proteins found in the blood of people with active TB in Africa and South America.
They compared the biomarkers to those found in healthy people and patients with lung infections. They identified 118 proteins that differed significantly between the groups. They then narrowed these down to six proteins that can be used to distinguish contagious patients with TB from people in good health or with lung conditions.
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Study co-director Dr Diana Garay-Baquero, also from the University of Southampton, said the findings are a roadmap to developing a new TB test. This could be as simple as the lateral flow tests used to identify Covid-19.
“The new markers we discovered are truly exciting. The important work now is to develop these into tests that can be used for the millions of people who are transmitting TB without knowing it. As the Covid-19 pandemic confirmed, we ignore highly infectious airborne diseases at our peril,” she said.
