WASHINGTON (AP) — It happens too often: A doctor isn't sure what's causing someone's feverish illness but prescribes antibiotics just in case, drugs that don't work if a virus is the real culprit.
Now 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, such as 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 Wednesday reported that a study involving 102 people provided early evidence that the test can work.
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, additional testing that can take days.
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,” said Duke lead researcher Dr. Aimee Zaas.
The test took 12 hours to get results. The researchers hope to speed that up.
Why would a doctor want to know merely that a virus is present and not which virus? That's enough information to rule out antibiotics, Zaas said. Unnecessary antibiotic use is one factor in the growing problem of drug-resistant germs, which are blamed for more than 23,000 deaths a year.
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