This article was originally posted on RealClearScience.
Viruses are pernicious beasts. Some of them can sneakily hide inside the body, long after the initial infection has been cleared. For instance, varicella zoster virus (VZV), a type of herpesvirus that causes chickenpox, survives in an inactive state inside nerve cells for the remainder of a person’s life. Then, for unknown reasons, it can reactivate, causing shingles in old people or even healthy 30-year-olds. Other viruses may play a role in chronic conditions such as asthma or inflammatory bowel disease. Continue reading