Rabies and Prions Flashcards
Source of rabies
Any mammal. Skunks, foxes, coyotes are common, bats are very common, rodents - rarer.
Rabies incubation
Can be days to years, travels from sensory nerve to CNS (longer distance, longer incubation). Once symptomatic, almost always fatal.
Rabies virus characteristics
-ve sense RNA, Rhabdovirus
Clinical presentation
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
Rabies diagnosis
Hx, clinical, biopsy - nuchal, CSF then detect Ag or do PCR
Rabies Antiviral treatmet
NONE. Invariably fatal once it has “begun”
Rabies treatment
Clean wound. Get Rabies Ig. vaccine - pre-exposure: for animal handlers; post-exposure: following animal bites
Rabies postexposure prohylaxis
Inactivated virus. Give several times (few days apart). Very safe (early vaccines had lots of issues)
Prions - what are they?
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.
Prion disease examples
Kuru, Crutzfel-Jakob diseases (cause dimensia), Variant CJD (ie mad cow)
Prion pathology
sponge appearance. No inflammatory cells (self protein, so no immune response)
Prion protein - what’s different?
Single a.a. mutation resulting in change in protein folding (less helix, more ß sheet). Requires some “normal” protein to be present too
Creutzfeld-Jakob Disease
Usually in older people. 80% sporadic. Progresses rapidly. Early onset Dementia (40-50), death within 3 years. 100% fatal.
Variant CJD
Onset is much younger. Associated with BSE contaminated beef (but there is a genetic disposition, not everyone got it). 100% fatal
BSE
sporadic cases will be reported. But extremely low risk to humans.
