Duke University researchers are developing a blood test to more easily tell when a respiratory illness is due to a virus and not a bacterial infection, hoping to cut the dangerous overuse of antibiotics and speed the right diagnosis.
It works by taking a fingerprint of your immune system — how its genes are revving up to fight the bug. That’s very different from how infections are diagnosed today. And if the experimental test pans out, it also promises to help doctors track brand-new threats, like the next flu pandemic or that mysterious MERS virus that has erupted in the Middle East.
That viral “signature could be quite powerful, and may be a game-changer,” said Dr. Geoffrey Ginsburg, Duke’s genomic medicine chief. He leads the team that on Wednesday reported that a study involving 102 people provided early evidence that the test can work.
- In the most recent experiment, 102 subjects with viral and bacterial infections, as well as healthy control patients, arrived at a hospital emergency room and were given the blood test. With about 90 percent accuracy, the test returned the proper diagnosis in just 12 hours.
Today, when symptoms alone aren’t enough for diagnosis, a doctor’s suspicion guides what tests are performed — tests that work by hunting for evidence of a specific pathogen. Fever and cough? If it’s flu season, you might be tested for the flu virus. An awful sore throat? Chances are you’ll get checked for strep bacteria. A negative test can leave the doctor wondering what germ to check for next, or whether to make a best guess.
Moreover, rapid in-the-office tests aren’t always accurate and can miss infections. So patients may have blood or other samples sent to labs to try to grow any lurking bacteria and tell if it’s to blame, additional testing that can take days.
“This is something we struggle with every day,” said Dr. Octavio Ramilo, infectious disease chief at Nationwide Children’s Hospital in Columbus, Ohio, who wasn’t involved in the new study. Particularly with children, a respiratory virus and a bacterial infection “in the beginning look completely alike,” he added.
Hence researchers at a number of universities are trying to harness a fairly recent discovery: As your immune system detects an invading bug, different genes are activated to fend off a viral infection than to fight a bacterial or fungal one. Those subtle molecular changes appear to be occurring even before you feel any symptoms. And they form distinct patterns of RNA and proteins, what’s called a genomic fingerprint.
The Duke team discovered 30 genes that are switched on in different ways during a viral attack. The test essentially is a freeze-frame to show “what those genes are doing at the moment in time that it’s captured,” explained Duke lead researcher Dr. Aimee Zaas, an infectious disease specialist.
But the virus-or-not question is just the beginning, Ramilo said. His research suggests genomic fingerprints also can distinguish a flu strain from other common viruses.
In larger studies set to begin as early as this flu season, scientists will look at ways of paring down the number of genes the test analyzes and reducing the test's turnaround time to as little as one hour. “We'd love to have the pregnancy test equivalent to viral infections,” Ginsburg said.
Woods, Ginsburg, and others have also filed for a provisional patent on the science behind the test. Their experiment was funded in part by the Defense Advance Research Project Agency (DARPA), an arm of the U.S. Department of Defense.
Many of the infectious samples the team used to develop the test came from the global H1N1 pandemic of 2009. Many H1N1 sufferers were not quickly diagnosed and treated, which allowed the disease to spread to even more individuals.
In addition to the early detection of naturally occurring global pandemics, the authors believe their test could also help the U.S. respond to a bioterrorism attack. “This could help screen people for exposure, perhaps even before they have fully developed symptoms,” Ginsburg said. “We hope it's an application, if it ever comes to that.”
Ginsburg said he expects medical technology companies will follow suit to develop smaller, more readily available diagnostic equipment for rapidly analyzing test samples. “Our hope is it could shut a pandemic down before it gets started,” he said.
The most immediate application, however, will be to curb the overuse of antibiotics. Patients often arrive at the doctor's office with a common cold, which is caused by a virus. Because the symptoms could falsely point to a bacterial infection, antibiotics are often prescribed.
Not only is the treatment futile, it lets bacteria learn to mutate and become more powerful, Ginsburg said, and wastes a patient's time and money.
In a brief statement to Healthline, the CDC said, “CDC welcomes new strategies and technologies that seek to curb unnecessary antibiotic use and resistance.”