Besides some isolated countries that are regarded rabies free classical rabies occurs worldwide. The disease is transmitted by rabid animals. Carnivors and viverids represent the principal reservoir species and are responsible for the maintenance of the infectious cycle and hence for the presence of the disease.

Hereby, a sylvatic and urban transmission cycle is differentiated.

Sylvatic rabies is characterized by the establishment of transmission cycles in one ore more carnivorous wildlife species. For example, in Europe the red fox (Vulpes vulpes) is the main reservoir species. In parts of Asia the racoon dog (Nyctereutes procyonoides) is a reservoir species for rabies. In eastern Europe, introduced raccoon dogs may be implicated in sustaining the chain of infection, too.

Within one geographic region different infection cycles may occur simultaneously, as in the Americas where independent rabies infectious cycles in raccoons (Procyon lotor), skunks (memphetis ssp), red foxes (Vulpes vulpes), grey foxes (Urocyon cinereoargenteus), coyotes (Canis latrans) and arctic foxes (Alopex lagopus) exist. Sporadically, rabies virus is transmitted to humans and domestic animals. Bat species can act as a virus reservoir, too. (See Rabies and Bats)

Urban rabies is by far more important for public health. Stray and feral dogs maintain and transmit the disease through bite inflictions, causing more than 50.000 human casualties annually. Mainly developing countries from Asia and Africa suffer from the burden of the disease. The WHO regards Rabies as a neglected disease and efforts are promoted to establish wider access to appropriate post-exposure treatment for humans. Dog rabies control by mass vaccination campaigns and dog population management are supported.