Rabies Flashcards
2 Forms of rabies
Encaphilitic/Furious (80%)
Paralytic (20%)
Etiology of rabies
ssRNA, Lyssavirus, rhabdovirus
Most important vector of rabies
Dogs
Incubation period of rabies
20-90 days, variable
Where rabies virus binds
nicotinic acetylcholine receptors on POSTSYNAPTIC membranes at NMJ
Spread of rabies virus
CENTRIPETAL along the peripheral nerves towards the CNS
Rate of up to ~250mm/d via RETROGRADE fast axonal transport to the SC or brainstem
Rabies replication
Initial: within striated muscles at site of inoculation
Later: acinar cells of the salivary glands, secreted in saliva of rabid animals
Rates of infection and mortality highest
bites on the face
intermediate: hands and arms
lowest: legs
Most characteristic pathologic CNS finding
Negri bodies (cytoplasmic inclusions within the neurons)
Responsible for clinical disease in rabies
neuronal dysfunction (rather than neuronal death)
Earliest specific neurologic symptoms
Paresthesias
Pain
Pruritus near the site of exposure (strongly suggests rabies)
Presents with early brainstem involvement
Encaphilitic: hydrophopia, aerophobia
with preservation of consciousness
Characteristic of paralytic rabies
Flaccid paralysis producing quadriparesis and facial weakness
Highly sensitive and specific for diagnosis of rabies
RT-PCR amplification
DFA testing for more rapid results
Period of observation for healthy dogs, cats and ferrets
10 days
