"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 for more than a few seconds. But inside an organism, this virus has been found living for about forty-eight hours after the organism died. This virus is found in the saliva of infected animals and can be passed to any worm-blooded organism. Almost always, this virus is passed when an infected animal bites a worm-blooded organism. Rabies can also be transmitted through the air, like in caves of bats. But the virus can only spread from the saliva of the infected. .
The host will first develop flu like symptoms, with malaise, fever, or headache, along with itchiness or discomfort at the site of the infection, lasting for days. As the disease progresses, the virus is received by the peripheral nerves and transported into the Central Nervous System, via sensory and motor nerves at the site of infection.