Rabies (Lyssa) is one of the oldest known zoonotic diseases; an animal disease transmissible to humans. It is caused by rhabdoviruses of the genus Lyssavirus and can affect all mammals including humans. Transmission occurs when there is direct contact to infectious saliva, i.e. bites, scratches, broken skin. The incubation period ranges in general between 2 and 3 month (2 weeks to 6 years are reported) depending on the site of infliction, the amount of virus and the virus strain.

Due to its neurotropism rabies viruses cause neurological symptoms (see clinical signs) that may differ in animals and humans. Once symptoms of the disease develop, rabies is inevitably fatal to both animals and humans.