TB test before symptoms is now step closer

SCIENTISTS have developed a technique that could identify tuberculosis months before symptoms begin.

A test for a gene signature in the blood was developed by a team led by the Francis Crick Institute and University of Leicester, in collaboration with French and South African researchers.

The scientists looked at 53 TB patients in Leicester and followed 108 of their close contacts over two years to see who developed active TB.

They found that those who remained healthy showed no sustained gene signature, while six of the nine who went on to develop active TB showed a strong, sustained signature.

It is the first study to link the presence of signature and the onset of early TB before the patient has symptoms.

The study could lead to new ways to detect and therefore treat the disease, which two billion people worldwide are infected with but which is latent in 90 per cent of cases.

Professor Anne O’Garra, group leader at the Francis Crick Institute, said: “Treating active TB before symptoms start could spare patients and their families from unpleasant symptoms, reduce the spread of disease and offer peace of mind to people who are not going to develop active TB.

“This study was a promising proof-of-principle, offering new insights into how to develop gene signatures for active TB.

“The next step will be to develop and test different gene signatures in larger groups of people, with the aim of being able to offer validated tests to patients within the next decade.”

Symptoms of active TB include persistent cough, followed by weight loss, fever and breathing dif- ficulties. TB can be fatal if left untreated, and even when treated promptly the symptoms can last for several weeks during which time the patient remains infectious.

Dr Pranab Haldar, of the University of Leicester, recruited a sample group in the city.

He said: “Being able to track TB patients’ contacts and take monthly blood samples gave us a unique insight into how immune responses develop.

“The next step will be to better understand what the different responses mean and we will need to study larger groups to achieve this.”