June 19 (UPI) -- A gene signature in the bloodstream could help doctors detect if someone might develop active tuberculosis long before symptoms show up, according to a new study.
Researchers in Britain, France and South Africa found the genetic signature, which could allow for diagnosis months before patients report symptoms, publishing the findings Tuesday in Nature Communications.
"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," senior author Dr. Anne O'Garra, a group leader at the Francis Crick Institute in Britain, said in a press release. "This study was a promising proof-of-principle, offering new insights into how to develop gene signatures for active TB."
The goal is to offer validated tests to patients within the next decade, after tests in larger groups of people show it to be useful.
Active TB symptoms include persistent cough, followed by weight loss, fever and breathing difficulties. And if untreated, TB can be fatal. Patients can be infectious for several weeks, even if treated promptly.
One-third of the world's population -- 2 billion people -- is infected with tuberculosis, and between 1.5 million and 2 million die from it each year, according to the World Health Organization.
With diagnosis before active TB, doctors could better prevent and treat the disease, the researchers said.
"Being able to track TB patients' contacts and take monthly blood samples gave us a unique insight into how immune responses develop," said Dr. Pranab Haldar, a senior clinical lecturer in respiratory medicine at the University of Leicester.
Previously, the researchers identified the full blood gene signature for active TB, and other groups have reproduced this signature in an attempt to narrow it to a few genes. Other researchers have found different gene signatures that also detected viral infection
While other researchers have found different gene signatures detected random viral infections, the 20-gene signature detected in the new study does not do so.
The researchers studied 53 TB patients in Leicester, following up with 108 of their close contacts during the following two years to see who developed active TB.
They tested the 20-gene signature with contacts of TB patients, finding those who remained healthy showed no sustained gene signature, but six of the nine who went on to develop active TB showed a strong, sustained signature.
"The ability of our signature to distinguish from viral infections is an important step forward for developing reliable tests that we can use in the clinic," Haldar said. "In the contacts we saw, the new 20-gene signature performed better than previous signatures but there is still work to be done."