New Blood Test Predicts TB 2 Years Before Onset

Researchers have developed a new blood test that can accurately predict the development of tuberculosis (TB) up to 2 years in advance among individuals living in the same household as someone with active TB.

The new test measures the expression of a 4-gene signature in the blood known as “RISK4,” the components of which are known to be associated with inflammatory responses. The test is designed to provide positive results to a smaller percentage of high-risk household members and, in turn, reduce the number of people who receive unnecessary treatment for TB prevention.
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The effectiveness of the blood test was determined in a study of 4466 HIV-negative, healthy participants from households of 1098 index cases of active TB in Sub-Saharan Africa. Blood samples were collected from each participant and stored. However, due to the costs of the tests, not all samples were tested.

A total of 79 participants whose blood was tested had progressed to active TB between 3 and 24 months of exposure, while the remaining 328 participants with available blood test results had stayed healthy over the course of follow-up. Ultimately, the researchers found that the blood test could accurately predict progression to TB up to 2 years prior to onset.

It is important to note that, although the individual components of the RISK4 signature cannot sufficiently provide an accurate diagnosis of prediction, “a combination of these markers improves its accuracy,” said Professor Gerhard Walzl, MMed, PhD, lead study author and leader of the Stellenbosch University Immunology Research Group in Tygerberg, South Africa, in a press release.

“This study is the first step, and now the impact of this test on prevention of TB will have to be tested in multicenter clinical trials,” Prof Walzl added. “In addition, the validity of the prediction in high-risk individuals in Asia, South America and other high-priority areas needs to be assessed.”

—Christina Vogt

Reference:

New blood test found to predict onset of TB up to two years in advance [press release]. American Thoracic Society. April 6, 2018. https://www.thoracic.org/about/newsroom/press-releases/journal/new-blood-test-found-to-predict-onset-of-tb-up-to-two-years-in-advance.php. Accessed on April 6, 2018.