Rabies and Prions

Question 1

Source of rabies

Answer 1

Any mammal. Skunks, foxes, coyotes are common, bats are very common, rodents - rarer.

Question 2

Rabies incubation

Answer 2

Can be days to years, travels from sensory nerve to CNS (longer distance, longer incubation). Once symptomatic, almost always fatal.

Question 3

Rabies virus characteristics

Answer 3

-ve sense RNA, Rhabdovirus

Question 4

Clinical presentation

Answer 4

Prodrome: fever, sore throat, chills, headache, pain at bite. Neuological: agitation, restlessness, hyperactivity, salivation. Leads to dysphagia (hard to swallow), stupor, coma, death in 4-20 days

Question 5

Rabies diagnosis

Answer 5

Hx, clinical, biopsy - nuchal, CSF then detect Ag or do PCR

Question 6

Rabies Antiviral treatmet

Answer 6

NONE. Invariably fatal once it has “begun”

Question 7

Rabies treatment

Answer 7

Clean wound. Get Rabies Ig. vaccine - pre-exposure: for animal handlers; post-exposure: following animal bites

Question 8

Rabies postexposure prohylaxis

Answer 8

Inactivated virus. Give several times (few days apart). Very safe (early vaccines had lots of issues)

Question 9

Prions - what are they?

Answer 9

When initially studied they thought it was a slow virus, but couldn’t find RNA/DNA. Basically they are some infectious proteins. Proved because it was resistant to nucleases, UV, etc.

Question 10

Prion disease examples

Answer 10

Kuru, Crutzfel-Jakob diseases (cause dimensia), Variant CJD (ie mad cow)

Question 11

Prion pathology

Answer 11

sponge appearance. No inflammatory cells (self protein, so no immune response)

Question 12

Prion protein - what’s different?

Answer 12

Single a.a. mutation resulting in change in protein folding (less helix, more ß sheet). Requires some “normal” protein to be present too

Question 13

Creutzfeld-Jakob Disease

Answer 13

Usually in older people. 80% sporadic. Progresses rapidly. Early onset Dementia (40-50), death within 3 years. 100% fatal.

Question 14

Variant CJD

Answer 14

Onset is much younger. Associated with BSE contaminated beef (but there is a genetic disposition, not everyone got it). 100% fatal

Question 15

BSE

Answer 15

sporadic cases will be reported. But extremely low risk to humans.

Question 16

Chronic wasting disease

Answer 16

Deer, elk. No human transition to date.

Question 17

Protein folding diseases

Answer 17

Include things like alzheimers. Potential to slow them with pharmaceuticals or vaccines.