prions and rabies

Question 1

differentiate the pathogenesis of prions vs rabies

Answer 1

prion- rare, progressive neurodegenerative diseases

long incubation period

spongiform changes assoc. with neuronal loss and failure to induce inflammation

rabies- entry into peripheral nerve ending, transits along neuronal pathway; incubation: 10 days-6 years

Question 2

modes of transmission for prions

Answer 2

sporadic, mutation in PrPsc gene, ingestion or inoculation of contaminated material (blood transfusion, corneal grafting)

Question 3

modes of transmission for rabies

Answer 3

zoonotic infection (dogs, bats, skunks, raccoons), transplant (not blood)

Question 4

clinical presentations and diagnosis of CJD (prion)

Answer 4

CJD- abnormal gait, vision

headache, dizziness, paresthesias

memory loss, speech abnormalities, anxiety, depression

hyperreflexia, spasticity

vegetative state w/I 1 year

diagnosis- clinical grounds, followed by western blot for PrPsc in tonsil biopsy, definitive dx by brain biopsy

Question 5

clinical presentations and diagnosis of rabies

Answer 5

malaise, anx, depression

itching pain, tingling at site of bite

agitation, hyperactivity, fluctuating consciousness, bizarre behavior

sore throat, hypersalivation, hydrophobia, flaccid paralysis

Question 6

the prion human diseases

Answer 6

Kuru, creuztfeldt-Jakob disease, variant CJD, gerstmann-strassler-scheinker syndrome, fatal familial insomnia

Question 7

the etiologic agent of prions

Answer 7

misfolded protein (PrPSc)

Question 8

describe pathology (stain, lesions) of prions

Answer 8

H&E stain
amyloid plaques in CJD- hyaline eosinophilic core, peripheral margin of radiating fibrils surrounded by a pale halo.

spongiotic changes in the cortex, loss of neurons

Question 9

Clinical presentation of vCJD

Answer 9

dysthesias, paresthesias, anx, depression, anorexia, social withdrawal

pyramidal tract dysfunction, rigidity, cerebellar dysfunction, myoclonus

duration of illness- 1 yr

Dx- clinical grounds, then western blot on tonsil biopsy for PrPsc protein; brain biopsy

Question 10

rabies pathogen causes..

Answer 10

viral encephalitis characterized by hydrophobia

Question 11

pathology of rabies

Answer 11

H&E stain; Negri bodies (cellular inclusions in the pyramidal cells and cerebellum)

Question 12

stain for rabies diagnosis

Answer 12

fluorescent antibody DFA stain

Question 13

treatment of rabies

Answer 13

rabies Ig; post-exposure vaccination

Question 14

characteristics shared by rabies and prions

Answer 14

transmission can occur through transplanted contaminated/infected tissue

long incubation period

fatal