Rabies is caused by a number of different strains of neurotropic viruses, most of which bwlong to the genus lyssavirus, family Rhabdoviridae.
The virion is bullet-shaped and contains single-stranded, non-segmented, negative sense RNA genome which encodes 5 structural proteins.
Susceptibility to infection is believed to be related a number of factors - the infecting strain of rabies virus, the host's genetic background, the concentration of nicotinic acetylcholine receptors in the skeletal muscle, the size of inoculum, the degree of innervation of the site of the bite, and its proximity to the central nervous system.
The virus usually amplifies in skeletal-muscle cells near the site of inoculation before entering the nervous system through unmyelinated sensory and motor terminals. Spread is by retrograde axonoplasmic flow (rate of 8 to 20mm per day) until it reaches the spinal cord. It is at this point that first specific symptoms of the disease occur - paraesthesia and pain at the wound site. Encephalitis occurs as the virus spreads through the central nervous system. Spread then occurs along peripheral nerves to other parts of the body, e.g. salivary glands where there is resultant shedding of saliva.
Last reviewed 01/2018