Worldwide, where approximately 50,000 people die each year from rabies, the highest risk of human infection is from rabid dogs. In the U.S., where domestic dogs are usually vaccinated, only occasional cases of human rabies usually occur, usually from the bites of wild animals. Rabies is thought to be the oldest communicable disease of humans. Usually the bite or scratch of an infected animal, which introduces the virus through the skin or mucous membrane. World-wide, rabid dogs cause most cases of the disease.
Rodent rabies is rare.
Aerosol transmission from an infected animal, usually a bat. There have been at least 6 recorded cases of humans contracting the disease from transplants of corneas from infected donors. The rabies virus attacks nervous tissue and appears to replicate almost exclusively in neuronal cells. Once introduced through the skin or mucous membrane, the virus begins replicating in the striated muscles at the wound site. The virus can replicate in muscle cells for hours or weeks, or it can migrate immediately to the nervous system via unmyelinated sensory nerve endings at the inoculation site.