Rabies is, of course, the most notorious of all zoonotic diseases. It's spread by a virus that is commonly found in raccoons, skunks, bats, and foxes. The disease can be spread by contact with saliva from an infected animal, whether from a wild animal or a pet dog that has had a brush with one. Rabies starts with flu-like symptoms. Without treatment, it leads to agitation, delirium, hallucinations, and partial paralysis. Worldwide, the disease causes 55,000 deaths a year. The rabies vaccine used to require painful shots to the abdomen, but the modern vaccine involves only three to five shots in the shoulder.