<P> Rabies is mostly transmitted to humans, and between animals, through the saliva of infected animals . Transmission is generally through a bite from any infected animal . </P> <P> Transmission between humans is extremely rare, although it can happen through organ transplants, or through bites . </P> <P> After a typical human infection by bite, the virus enters the peripheral nervous system . It then travels along the nerves towards the central nervous system . During this phase, the virus cannot be easily detected within the host, and vaccination may still confer cell - mediated immunity to prevent symptomatic rabies . Once the virus reaches the brain, it rapidly causes encephalitis and symptoms appear . This is called the "prodromal" phase and at this time, treatment is usually unsuccessful . Rabies may also inflame the spinal cord producing myelitis . </P> <P> Any mammal may become infected with the rabies virus and develop symptoms, including humans . But dogs are, by far, the main source of human rabies deaths, contributing up to 99% of all rabies transmissions to humans according to the World Health Organization . Infected monkeys, raccoons, foxes, skunks, cattle, wolves, bats, and cats are also known to transmit rabies to humans . Rabies may also spread through exposure to infected domestic farm animals, groundhogs, weasels, bears and other wild carnivores . Small rodents such as squirrels, hamsters, guinea pigs, gerbils, chipmunks, rats, and mice and lagomorphs like rabbits and hares are almost never found to be infected with rabies and are not known to transmit rabies to humans . Vampire bats can transmit rabies to humans in the' new world' tropics . </P>

Who discovered the transmission of the rabies virus spread by vampire bats