Researchers, including one of Indian origin, have developed a new blood test that could predict the development of tuberculosis (TB) three to six months before people become unwell, an advance that may help better treat the disease, and save countless lives.
In the study, published in The Lancet Respiratory Medicine journal, researchers sought to identify which gene expression signatures in blood could be used to predict the disease before symptoms arise.
"The emergence of gene expression signature tests, which can aid diagnosis and early treatment, provides real hope for the management of infectious diseases," said study lead author Rishi Gupta from the University College London (UCL) in the UK.
"In this study, we identify multiple signatures to identify the onset of tuberculosis, which is extremely encouraging, potentially providing multiple targets for early detection," said Gupta.
The researchers noted that gene expression signatures are being tested in a range of diseases to aid diagnosis, prognosis or prediction of the response to treatment.
Gene expression signature is a single or combined group of genes in a cell with a uniquely characteristic pattern of gene expression that occurs as a result of an altered or unaltered biological process or pathogenic medical condition.
Some are already being used to support the management of cancers, but none have reached the clinic in infectious diseases, such as TB, the researchers said.
For the latest study, the researchers initially conducted a systematic review of published gene signatures found to be present in blood samples from people with TB, compared to healthy individuals.
From this, 17 candidate gene expression signatures for TB were identified, and tested in more than 1,100 blood samples in published data sets from South Africa, Ethiopia, The Gambia, and the UK.
The scientists analysed samples from people who had no TB symptoms at the time they gave blood. Those people were then followed up to identify which participants developed TB in the subsequent months.
The researchers found that eight of these signatures, including measurement of expression of a single gene, could predict the diagnosis of TB within three to six months, which falls within the accuracy required by the World Health Organisation (WHO) for new diagnostic tests.
This accuracy was achieved by revealing the patients' immune responses to bacteria before the symptoms of the disease develop, the researchers said.
"Further development of these tests could help identify people who will benefit most from preventative antibiotic treatment, in order to reduce the occurrence of tuberculosis -- a disease which causes the greatest number of deaths worldwide due to any single infection.
"The availability of multiple signatures will help to broaden access to these tests," Gupta said.
Tuberculosis is a disease caused by a bacteria (Mycobacterium tuberculosis) that most often affects the lungs, according to the researchers.
TB is spread from person to person through the air. When people with lung TB cough, sneeze or spit, they propel the TB germs into the air, they said.
The researchers noted that worldwide, TB is one of the top 10 causes of death and in 2018 1.5 million people died from the disease.
"About one-quarter of the world's population is thought to have been infected with the bacteria that cause TB. The majority of these individuals remain well and cannot transmit the disease," said Professor Mahdad Noursadeghi from UCL.
"Our findings establish the gene signatures in blood which show most promise for identifying people who are at risk of disease. Future development of a blood test based on these findings could make an important contribution to efforts to reduce the impact and spread of this deadly infection," Noursadeghi said.
(With inputs from PTI)
