7 - Rabies Flashcards
(53 cards)
In latin, rabies means…
Madness, rage, fury
How many rabies cases worldwide? How many due to dog bites? Where do most deaths occur?
~60,000 deaths worldwide (most children in developing countries)
95% cases due to dog bites
99% deaths occur in Africa and Asia
Incubation period of rabies? signs of furious rabies
Typically 2-3 months, range from 1 week to 1 year
Furious rabies = signs of hyperactivity, excitable beh, hydrophobia, aerophobia. Cardio-respiratory arrest =death
Rabies dates back to…
Mesopotamians
Owner of a rabid dog was responsible for containment of the animal; pays for deaths
Aristotle on Rabies.
“Dogs suffer from the madness, this causes them to become irritable and all animals they bite become diseased”
Occurrence of rabies in europe and the americas
- few human deaths
- few transmissions from dogs (vaccinated)
- primarily via wildlife (bats, foxes, skunks, raccoons)
Name countries that are recognized by the CFIA as being free of rabies
- Australia
- Finland
- Ireland
- UK
Canada rules on dog importation
It is restricted due to prevalence of rabies in some countries
Rabies vaccination required
Basics of the WHO’s response to rabies
- involve all countries, emphasize one health approach
- access to prophylactic treatment
- can validate countries achieving 0 human deaths due to dog rabies
OIE is now the… What are their objectives
World Organization for Animal Health (WOAH): international org funded by UN
Objectives: transparency, scientific info, promote vet services, food safety, animal welfare
What % of dogs need to be vaccinated so no more human cases occur?
70%
What kind of virus is rabies? Shape?
RNA virus
Rhabdovirus family, Lyssavirus genus
Bullet shaped
Three Lyssavirus subgroups, what diseases they cause
Phylogroup 1: rabies virus, european bat lyssaviruses, australian bat lyssavirus
Phylogroup 2: lagos bat lyssavirus, mokola lyssavirus
Phylogroup 3: west caucasian bat lyssavirus
Describe the rabies RNA genome
12 kb negative sense genome
When it enters cell must be converted to positive sense through RNA polymerase
Outer coat of rabies virus? What does it do
Glycoprotein membrane
Interacts with cellular membrane to gain entrance into a cell; also is the target for neutralizing antibodies (antibodies to virus = antibodies to G protein)
Rabies virus is inactivated by:
Heat (50C for 15 min)
Sunlight, desiccation
Five structural proteins of the RNA virus
- N nucleoprotein
- P phosphoprotein
- M matrix protein
- G glycoprotein
- L RNA dependent RNA polymerase
Majority of human rabies from dog reservoirs are in what countries?
South America, Asia, India
Stages of rabies virus spread in the body
- peripheral nervous system to brain: 3-12 weeks
- virus replicates rapidly in the brain
- subsequent centrifugal spread to salivary glands and saliva
- clinical symptoms after virus enters brain = death within 1 week
Slide 29
When does rabies treatment need to occur? Why?
PRIOR to clinical signs (post-infection)
Takes so long to progress to the brain, so it works
Why is there little/no rabies transmission during the preclinical phase
Because transmission occurs from saliva, which does not get infectivity until after brain infection
How does rabies spread in the body
Neurotrophic: spreads along neural pathways and invades CNS
Travels to spinal cord at a rate of 50 to 100 mm/day
Why are clinical symptoms not useful for detecting rabies in dogs
Most of the infection is incubation or preclinical
Clinical symptoms can be difficult to identify
Three methods of rabies detection
Direct Fluorescent Antibody Technique:
- brain tissue
- look for antibodies against viral nucleoprotein
Polymerase Chain Reaction
- primers to rabies genome
Direct Rapid Immunohistochemical Test:
- light microscopy
- used for wildlife surveillance
