RABIES Flashcards
Talk about rabies Family Genus Genone What does it cause How transmisste
- Family Rhabdoviridae
- Genus Lyssavirus
- Negative sense SS RNA virus
- enveloped
- causes fatal encephalitis affecting all warm blooded animals
- transmitted in slaiva of infected animal but bites or scratches
Nearly always fatal
Rabies incubation period
7 days to many months:
50% within a month, 80 by 4
is variable and is believed to be due to a number of factors including the site and severity of the bite, the virus strain and the host bitten. A severe bite to the face is more likely to result in a very short incubation period (small distance to CNS) than a minor exposure to a peripheral site
PAthogenesis Rabies
- highly neurotrophic
- bite site = slow multiplication of virus in muscle cells (incubation)
- Rapid transport of virus in nerve axons via CNS to brain
- Rapid spread within CNS
- Transport in nerve axons to peripheral organs inc salivary glands
- virus transiently excreted in saliva
- Massive viral replication in salivary glands
- Infection of different areas of brain = abnormal behaviour combined with viral excretion enhanses onwasrd trnasmission of virus - aggression, not as wary of humans etc
What are the 2 common forms of rabies
Paralytic / Dumb rabies “bone in the throat syndrome” or Furious rabies
What is the phase before?
Clinical signs
The prodromal phase. Ususally see: Behavioural changes Temperature rises Pupils dilated Excessive salivation - virus can be shed here.
Difference in furious and dumb form dogs
Furious form (20%)
a) Agitated, aggressive
b) phonation
c) difficulty in swallowing
d) seizures - muscular incoordination
e) Paralysis, coma & death
f) incoordination, paralysis & death
Dumb form (>70%)
- dropped jaw
- bone in throat
- incoordination, paralysis & death
- how many children get infected as go up to dog
What to rememebr about rabies
No hard and fast rule to rabies clinical signs and incubation. Can see zero clinical signs
non pathognomic
Rabies epidemiology - cycles
2 types
- Urban rabies
- Sylvatic rabies
Talk about urban rabies
Reservoir species: domestic dog
Accounts for vast majority human cases
Talk about sylvatic rabies
Also known as wildlife rabies
Reservoir sepcies: wild animals, fox, skunk, raccoon, bat.
Often cause of rabies in cattle, sheep and horses
Epidemiology of rabies in Europe
- Classical rabies virus - majority western free, some eastern
- European bat lyssavirus type-1- detected in UK!
- European bat lyssavirus type-2 - same as above
- Bokeloh Bat Lyssavirus - we have the bats
- Lleida Bat Lyssavirus
- Kotalahti Bat Lyssavirus
both wildlife and domestic rabies are much more in eastern europe
Last 2 no protection agaisnt current vaccine!
Risk factors of rabies
- Risk of importation (infected animal) - think when owner brings in a pup!
- Complacency through lack of border control
- Emerging lyssaviruses – vaccine efficacy
- Multiple susceptible species
- New animal reservoir through host adaptation
- Political instability
- Lack of resources / reprioritisation
- Poor surveillance / infrastructure
- Poor collaboration (vet/public health)
- Poor education programmes
What to do if in a raboes endemic area and nipped by any animal
MUST seek post exposure prophylaxis if nipped in a rabies endemic area
Primary diagnosis rabies
Post mortem brain section, look at brain stem, hypocampus, medulla, cerebellum.
Stain brain impression with immunofluorescent strain which detects rabies virus antigens
What is the current law on pet travel from UK to EU and rabies
Since dec 2020 now UK has listed status, means all animals travelling to europe from UK will need to be vaccinated, won’t need serological test though
