Around one third of the world’s population is infected with the tuberculosis bacteria, and one in ten of those will get full-blown TB. It’s a mark of world poverty – poor living conditions mean it’s easily spread through the air to family members, and global incidence is growing by 1 per cent annually, with 5,000 people dying each day. Africa and Asia are especially badly hit. As far as global health problems go, TB is one of the big three, with Aids and malaria.

But current techniques of diagnosis and treatment are still slow and clunky. For years, organisations such as the World Health Organisation and the Bill and Melinda Gates Foundation have been saying the secret of getting on top of TB is not only finding more effective treatments, but developing quicker, better diagnostic tests. You need a test that is not only accurate and cheap, but gives such an instant result that treatment can start at the time a patient first visits a clinic.

Until this year, that goal seemed a long way off. The current standard test involves taking a sample of sputum coughed up from the lungs, and “culturing” it to see if the bacteria that grow from it are TB. That can take six weeks – by which time the person being tested may well have infected others (each person with active TB infects 15 others every year), or in a country like Africa may simply have gone away and be untraceable. It’s also inaccurate in 50 per cent of cases.

Then parasitologists, infection specialists and computer scientists at St George’s Hospital, London, came up with a completely new take on diagnosis. They found a way of “fingerprinting” for tuberculosis using simple blood tests – not looking for the bacteria themselves, but looking for protein markers in the blood that indicate whether TB bugs are around.

Similar blood techniques are currently used to tell whether cancers are active or not, and several diseases leave a molecular signature in the blood. But these distinguishing traces can be extremely difficult to pinpoint, because they involve subtle changes in dozens of substances. The St George’s researchers could do it because of new mass-spectrometry analysis techniques, and by using software which could analyse combinations of proteins and recognise distinctive patterns.

They came up with a profile of 20 proteins that could predict the presence of TB bacteria with 94 per cent accuracy. And then they whittled down that formula to just four proteins that could predict with 78 per cent accuracy. In other words, they’d not only proved the principle that there was a TB fingerprint test that was far more quick and accurate than current tests – they’d shown that it could be simple and cheap, too. Lead researcher Dr Delmiro Fernandez-Reyes hopes that the test could be in use globally in five years.

His paper, published in the medical journal The Lancet this September, went largely unheralded, but both the researchers and the Medical Research Council are finding it hard to contain their excitement. This isn’t one of those bits of research that might make the comfortable, long lives of the European middle classes just a little longer, or a little more comfortable. It’s something that could save the lives of millions who are currently dying prematurely and unnecessarily. “It’s very basic science in a way,” says Fernandez-Reyes, “but it has very straight-ahead and direct implications for human health globally.”

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