With tuberculosis being around for as long as it has, and killing as many people as it has, it’s hard to imagine that we haven’t managed to come up with an accurate way of testing for it by now. A group of researchers from the Stanford University School of Medicine claims to have come up with a new blood test that accurately diagnoses tuberculosis.
Inaccuracy in TB tests
Infecting 9.6 million people every year and killing 1.5 million of them, tuberculosis is one of the most infectious and dangerous diseases we have ever seen. About one third of the world is believed to be infected, either with an active or an inactive form of the disease.
The problem with testing for it is that prior to the development of the new procedure, we had pretty much no way of differentiating between active and non-active forms of the virus, and not even between infected people and people which had only gotten the vaccine (most countries administer the TB vaccine to their citizens), or even between TB infections and patients suffering from HIV.
Some of the most common ways to identify the disease are interferon tests, skin prick tests, and the always fallible sputum tests. For these last ones, patients are required to be able to produce phlegm on demand, and if they can’t do it, the test can’t really be performed.
The new procedure
With the incredibly low accuracy and detection rates, the World Health Organization has challenged researchers to come up with better procedures. This was happening in 2014, and now we might finally have a way to more accurately screen for the dangerous bacterium.
Requiring only a blood sample, the new screening can be performed in pretty much every country around the world with even a minimum of medical capabilities – it can even be performed under field conditions with just a PCR machine.
The test works by identifying three genes whose expression changes when affected by the TB bacterium. By using a sample of 1,400 different human samples from 11 separate data sets, the team developed the procedure which not only has an 86%-99% accuracy, but which can also determine the efficiency of the undertaken treatment.
By 86% to 99% accuracy I mean that the test is 86% accurate in children not suffering from the disease (which can simply be remedied by another subsequent blood test), and it is 99% accurate if the child patient does suffer from the active form of the disease.
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