Researchers at Duke Medicine have developed a diagnostic blood test that could prevent overuse of antibiotics by identifying viral infections in patients with acute respiratory symptoms.

The test uses genetics to identify, with more than 90 percent accuracy, viral illnesses that were previously hard to diagnose and are often treated with ineffective antibiotics. The test, reported in Science Translational Medicine Sept. 18, could be effective in both a clinical setting and in a pandemic, when there is pressure to diagnose quickly and accurately.

“There is a terrible need to develop new diagnostic tests to reduce inappropriate antibiotic use,” said Dr. Chris Woods, director of graduate studies at the Duke Global Health Institute and chief of infectious diseases at Durham VA Medical Center. “One of the areas where antibiotics are overused is when patients present with signs and symptoms that aren’t distinguishable between viral and bacterial infections.”

The overuse of antibiotics wastes resources and negatively impacts the health of misdiagnosed patients, said Dr. Geoffrey Ginsburg, director of genomic medicine at the Institute for Genome Sciences and Policy and co-senior author of the paper.

“We wanted to get a handle on whether or not an infection was viral to keep people from reflexively handing out antibiotics," he said.

The test looks in blood samples for a "genetic signature" known to appear during an immune response to a viral infection. This is a shift from the old method of testing for the pathogen itself.

“We wanted to develop an assay that could be used in a more diagnostic clinical setting that was really good at separating out viral infections from bacterial infections,” Ginsburg said.

Using this method, researchers tested 102 patients that came to the Duke Hospital emergency room with a fever. Of the two influenza strains detected, the test respectively diagnosed the viral infections with 100 and 87 percent accuracy.

Research into an effective presymptomatic test for viral infections was funded in part by the Defense Advanced Research Projects Agency, a branch of the U.S. Department of Defense that researches new technology. The agency’s aim was to develop a method to identify individuals likely to become sick to limit the spread of infectious disease within military housing, Ginsburg said.

“Our original research was designed to look at a military setting, to identify individuals about to get sick and keep them out of harm’s way,” said Dr. Aimee Zaas, associate professor of medicine and lead author of the paper.

Though developed for the military, this test could have critical applications in clinical and public health settings, as well.

Such a diagnostic tool could be critical at the outbreak of a pandemic, Woods said. Before the development of this method, a specific reagent would have to be created to identify a new virus before any diagnoses could be done. This new test could indiscriminately figure out whether or not an infection was viral without having to determine what the pathogen is first.

“There’s a very robust response to viruses in humans, and if you have one, this assay will pick it up. You don’t need to know what it is,” Ginsburg said. “We’re turning the whole approach on its head.”

The research team has already begun expanding and perfecting this discovery to make it available in military and clinical settings as soon as possible. Following the success of the test in a handful of upper respiratory viruses, researchers said they are optimistic that their new test could accurately diagnose a variety of other infections that affect other systems, as well.

While working to make the test more time efficient and gaining Food and Drug Administration approval, Woods has begun research into using the method as an all-encompassing diagnostic tool. The new tool would combine processes to detect bacterial or fungal infections and predict which patients require intensive care or are at risk of dying.

“We hope that, conceivably within the next three or four years, we’ll have something available to primary care physicians and to the community at large,” Ginsburg said.