A hantavirus outbreak aboard a luxury cruise ship that has left three people dead is veering into the fringe. Online, a growing number of social media users are floating ivermectin as a possible treatment for the rare infectious disease, which can cause life-threatening heart and lung complications. Yes, you read that right — the antiparasitic drug used in livestock that became a pandemic-era flashpoint after being touted by media figures, politicians and even some doctors as a Covid cure is back in the spotlight. “Hantavirus is a RNA virus, and ivermectin should work against it,” Dr. Mary Talley Bowden, a...