Yellowstone National Park officials are warning travelers to steer clear of wildlife after a “zombie” deer was found dead near Yellowstone Lake, a hotspot inside the heavily-visited natural landmark. The deceased adult mule deer suffered from chronic wasting disease, or CWD, a contagious and fatal sickness that infects deer, reindeer, elk and moose, causing zombie-like symptoms including excessive drooling, drooping ears, head tremors, teeth grinding, and reluctance to move. There is currently no vaccine or known treatment for the disease.