New blood test can detect TB two years in advance

Scientists have found a new blood test that can accurately predict the development of tuberculosis up to two years, before its onset in high-risk patients. Those living with someone with active TB are at highest risk for developing the disease, yet only 5-20 per cent of people infected with tuberculosis develop TB, says a study published in American Journal of Respiratory and Critical Care Medicine.

The researchers developed and validated a blood test that measures the expression levels of four genes that can more accurately predict the development of TB in high-risk patients. “We found that this prediction (up to two years before the onset of the disease) is possible through measurements of a combination of a four-gene signature in the blood,” said Gerhard Walzl from Stellenbosch University in South Africa.

This signature, known as ‘RISK4’, is a combination of four genes associated with inflammatory responses. “The individual components of this signature may not be sufficient to deliver an accurate diagnosis of prediction, but a combination of these markers improves its accuracy,” said Walzl. “We are hoping that primary health clinics will be able to use such a test and the reagents would then be readily available in that format, similar to the tests that are currently used to diagnose TB,” he said.