HEALTH: Every Virus a Person Has Had Can Be Seen in a Drop of Blood, Researchers Find. “Using less than a drop of blood, a new test can reveal nearly every virus a person has ever been exposed to, scientists reported on Thursday. The test, which is still experimental, can be performed for as little as $25 and could become an important research tool for tracking patterns of disease in various populations, helping scientists compare the old and the young, or people in different parts of the world. It could also be used to try to find out whether viruses, or the body’s immune response to them, contribute to chronic diseases and cancer, the researchers said.” I predict that we’ll eventually discover that there are a lot of viruses with no obvious symptoms that nonetheless play a major role in people’s mental and physical health.