New blood test predicts onset of TB
STELLENBOSCH University researchers, as part of an international consortium, have developed a simple blood test that can predict the development of tuberculosis (TB) up to two years before its onset in people at high risk of developing the disease.
The university’s Immunology Research Group head and lead author of the study, Professor Gerhard Walzl, said people in close contact with TB patients are at risk of also developing the disease. However, it is not feasible to give preventative treatment to everyone who comes into contact with the patient.
“Our research group developed a blood test that can predict which contacts are more likely to progress to active TB, and these individuals can then be singled out for preventative treatment,” he said.
The team’s research was published on Friday in the American Journal of Respiratory and Critical Care Medicine, a US Thoracic Society journal.
Tuberculosis, caused by infection with myobacterium tuberculosis, is the world’s leading cause of death brought on by a single pathogen.
A blood test that predicts the development of TB without putting large numbers of lower-risk people through unnecessary preventative treatment is not currently available, Walzl said.
“Preventative treatment is several weeks long and has potential side effects.
“One wants to limit the number of people who have to undergo such treatment to those most at risk for developing active TB.”
The test measures the expression level of four genes associated with inflammatory responses. This four-gene signature, known as “RISK4”, was found to apply in populations from South Africa, The Gambia and Ethiopia.
“This study was the first step and now the impact of this test on the prevention of TB will have to be tested in multi-centre clinical trials.
“In addition, the validity of the prediction in high-risk individuals in Asia, South America and other high-priority areas needs to be assessed.”
The researchers aim to develop tests that will be used at primary health clinics, similar to the tests that are currently used to diagnose TB.
The work resulted from a Grand Challenges in Global Health initiative that was launched in 2003 by the Bill and Melinda Gates Foundation, in partnership with the National Institutes of Health (NIH), to support groundbreaking research projects.
The work stems from a 14-year collaboration of researchers from Europe, Africa and the US.
Co-funding was provided by the NIH, EU, the Wellcome Trust and the SA Medical