Rabies

Rabies is a fatal viral infection transmitted via saliva of infected animals that affects the central nervous system (CNS).

Rabies is caused by a neurotrophic single-stranded RNA virus from the Rhabdoviridae family.  Exposure usually occurs when patients come into contact with contaminated saliva from an infected animal after a bite.  The virus replicates locally within the muscle tissue of the bite wound for several days or weeks.  It contains a bullet-shaped envelope with knob-like glycoproteins that allows it to attach to the nicotinic acetylcholine receptor at the neuromuscular junction; the virus then travels in a retrograde fashion through peripheral nerve axons to the dorsal root ganglia.  From there, it rapidly ascends the spinal cord and initially infects the brainstem and hippocampus; it eventually spreads throughout the rest of the brain from that point.  Within the CNS, the virus causes neuronal inflammation, leading to the characteristic clinical picture.