$25 Blood Test Finds Every Virus You've Ever Had

Blood tests can reveal a lot about you, from your suicide risk to your need for antibiotics. Now, researchers at Howard Hughes Medical Institute say a simple blood test can identify every virus you've ever had. From just a single drop of blood, VirScan can detect the remains of more than 1,000 strains of 206 viruses that are infecting or have ever infected a patient, Discover reports via a Science study. The cost: about $25, reports RedOrbit. Essentially, the immune system creates new B cells designed to battle a particular virus; those cells make the antibodies that bind to and inactivate the virus, and identifiable traces of those antibodies remain in the blood—ready to fight the virus again should it return.

Previously, doctors could only test for antibodies to one virus at a time. But VirScan can search for hundreds of antibody reactions simultaneously, Popular Science reports. After screening blood from 569 people on four continents, experts found people were exposed to 10 viruses on average; two had antibodies for 84 different viruses. Study author Tomasz Kula makes clear one advantage of VirScan: "You can look at viral exposures in an unbiased way without having to suspect a particular infection ahead of time." That could help patients with undiagnosed diseases, including, for instance, Hepatitis C. Kula points out Hepatitis C can spur liver damage and cancer, often "because patients do not show symptoms for many years and so they did not get tested for this particular virus." (Read how a college dropout revolutionized blood tests.)