"Rabies, acute, contagious infection of the central nervous system, caused by a specific virus that enters the body through the bite of an animal. All warm-blooded animals are susceptible, but in North America the disease is most common in skunks, foxes, bats, raccoons, dogs, and cats. Most of the cases of rabies in humans are caused by the bite of one of these animals. The incubation period in humans varies from three weeks to 120 days, with an average of about four to six weeks. Rabies is virtually always fatal when vaccine is not administered. (http://encarta.msn.com/encyclopedia_761562378/Rabies.html)
Cases of rabies being reported date as far back as 300 BC, but the way this virus was spread throughout organisms was not discovered until late 1804's. It was until 1884 that a French bacteriologist, Louis Pasteur, found a vaccine that could actually prevent rabies from infecting an organism. His methods are still used by the most recent medicine and doctors. This vaccine has greatly aided in the lowering of human deaths from this disease throughout the years.
Rabies comes from Rhabdoviridea family. This virus is a parasite since it cannot live outside a host body