Rabies, Prions, Slow Virus Infections

Question 1

Rabies

Answer 1

An acute, fulminant, fatal encephalitis
Rabies virus, rhabdoviridae
Bite of rabid animal
Host: warmblooded animals, incl humans

Question 2

Rhabdoviridae

Answer 2

Rod or Bullet shaped

Question 3

Rabies pathogenesis

Answer 3

Centripetal (retrograde fast axonal transport)
-muscle /ct at site of inoculation
-NMJ-PNS-CNS
Centrefugal (fast axonal transport)
-CNS- PNS- salivary glands & other tissues

Question 4

Rabies clinical findings

Answer 4

Incubation period: 1-3mos

Prodormal phase: 2-10 days anxiety agitation

Neurologic phase: 2-7 days
encephalitic / furious rabies (80%)

Paralytic/dumb/apathetic rabies (20%):
2-10 days
Generally survive a few days longer

Coma/death: 0-14days

Question 5

Rabies diagnosis

Answer 5

Animal capture:
Rabid/suspected rabid: sacrificed
immediately, exam of neural tissue
negri bodies
Other animals: 10days observation
Signs of encephalitis: brain tissue exam
Direct flourescent antibody testing of brain tiisue of captured / eutanized animal

Question 6

Cat 1

Answer 6

Touching of feeding animals, licks on intact skin

None

Question 7

Cat 2

Answer 7

Nibbling of uncovered skin, bites, scratches or abrations w/o bleeding

Vaccine
Local treatment

Question 8

Cat 3

Answer 8

Single/multiple bites/scratches
Licks on broken skin
Contamination of mucous membrane with saliva from licks, contact w bats

Vaccine + Ig
Local treatment

Question 9

Rabies Vaccine

Answer 9

Human diploid cell vaccine (HDCV)
Grown from cell lines

Purified chick embryo cell vaccine (PCEC)
Grown in chicken fibroblasts

Question 10

Rabies antibodies

Answer 10

Rabies immune globulin, human (HRIG)

Antirabies serum, equine
When HRIG is nit available

Question 11

Prions

Answer 11

Proteinacious infectious particles
Misfolded prion proteins

Prion protein (PrP) found in normal brain
tissue of animals
PrP sc (scrappie)

Transmissible spongiform encephalopathies
Neurogeneration & spongiform changes
Long incubation periods (mos to decades)
followed by chronic progressive disease
(Weeks to years)

Always fatal

Question 12

Sheep & goat

Answer 12

Scrapie

Question 13

Cattle

Answer 13

Bovine spongiform encephalopathy
Mad cow disease

Question 14

Humans

Answer 14

Kuru -due to cannibalism
Creutzfeldt jacob disease
-Develops gradually w progressive
dementia, ataxia, myoclonus, & leads to
death in 5-12mos
-lateogenic cjd