What's up you guys? I work in pest control for Truly Nolan and have for years. Basically, the ha virus comes from rats. And when they drop their feces everywhere, along their Trail lines, it dries out becomes very powdery in it becomes airborne and then you breathe it in and it gives you a horrible horrible pneumonia type illness that can obviously even cause death. It's no joke. That's why when you have rats in your house you get them out as soon as possible because you have no idea what's going on between those walls.