diseases final (rabies) Flashcards
what is the definition for rabies
an acute viral encephalomyelitis. it is a natural disease of dogs, cats, bats, and wild carnivores. all warm blooded animals are susceptible and the degree of susceptibility varies
what is the etiology of Rabies
Rhabdovirus
is rabies killed easily by sunlight, heat, and disinfectants?
yes
how is rabies transmitted
- from the bite of an infected animal (this is the most common route)
- airborne (from cave dwelling bats) (this is rare)
- ingestion (from infected tissue, urine feces) (this is rare)
virus may be present in the saliva and transmitted by the bite of an infected animal ________ ________ prior to the onset of clinical signs (rabies)
several days
what are the 6 most common hosts for rabies
- dogs and cats
- skunks
- foxes
- raccoons
- bats
- coyotes
what is the most important host of human rabies worldwide
dogs and cats
where do the highest incidence of rabies occur in dogs and cats
the highest incidence of rabies in dogs and cats occurs in areas where wildlife rabies is epizootic
what animal is the most important reservoir of rabies in California, the north central states, and the south central states?
skunks
how can you tell that a skunk is rabid just by looking at it
rabid skunks will roam aimlessly during daylight hours and often attack anything that moves
why should skunks not be kept as pets (rabies)
long term subclinical infections in skunks are a major concern, the stress of capture and captivity may trigger clinical rabies, therefore, skunks should not be kept as pets
foxes have a higher incidence of rabies where
Canada
raccoons with rabies are a major reservoir for what
for rabies in southeastern states and states along the eastern seaboard
what animal represents the majority of cases of wildlife rabies reported in the US
raccoons
what animal is currently the most important wildlife source of rabies for humans
bats
what is the pathogenesis of rabies
IM viral inoculation usually occurs via a bite wound> virus multiplies in muscle cells> spreads to the NMJ> virus enters peripheral nerves> transport of virus up the peripheral nerve to the CNS then occurs
what happens if the bite is on the extremity (rabies)
the virus will reach the spinal cord first and then it will travel to the brain probably by the CSF
what happens if the bite is in the head region (rabies)
the virus will move along a cranial nerve and go directly to the brain
once the virus is in the brain what does it do (rabies)
once the virus is in the brain it will eventually make it to the limbic system of the brain (this leads to rage and a desire to attack)
where does the virus go after it has replicated in the CNS
the virus moves out of the brain via the cranial nerves> the salivary glands are then infected with the virus> paralysis of these muscles leads to an inability to swallow and dropping of the lower jaw (commonly seen in dogs)
what is the fear of water called
hydrophobia
what does incubation period mean
the time period between the time of initial exposure to a pathogen and the appearance of the first clinical signs of infection
what is the incubation period for rabies for dogs
2 weeks to 6 months
what is the incubation period for rabies for cats
2 weeks to 6 weeks
what is the incubation period for rabies for humans
2 weeks to 23 months (usually 1 to 3 months)
how long is the brief period before the onset of neurologic signs (rabies)
1-5 days
how long is the prodromal stage of rabies for dogs
1-3 days
what are the clinical signs of the prodromal stage of rabies
- behavior changes
- pupillary dilation, sluggish corneal, palpebral reflexes
- pruritus at the site of exposure
how long is the prodromal stage of rabies for cats
1 day
how long is the furious stage of rabies
1 -7 days
what are the clinical signs of the furious stage for dogs
- restlessness
- irritability
- excitability
- photophobia
- may bark at imaginary objects
- roam, vicious attacks when provoked by external stimuli
- may eat unusual objects, especially wood
- muscular incoordination, disorientation, seizures
what are the clinical signs of the furious stage for cats
more consistently develop the furious stage, may run continuously until die of exhaustion
how long does the paralytic stage of rabies last
2 to 4 days
what are the clinical signs of the paralytic stage rabies for dogs
- progressive paralysis from the site of injury to the entire CNS
- cranial nerve paralysis
- change in voice
- salivation
- dropped jaw (if the bite occurred on the face, these signs will develop first before paralysis occurs anywhere else)
- death follows coma
- respiratory paralysis
what are the clinical signs of the paralytic stage of rabies in cats
- mandibular, laryngeal paralysis is less common
what are the clinical signs of humans with the furious form of rabies
- fever
- headache
- anxiety
- nervousness
- and hyperesthesia at the site of the bite
- excitability, restlessness, hyperkinesis, and violent behavior
- salivate incessantly and refuse water due to pharyngeal spasms (hydrophobia)
- death occurs during convulsions or because of paralysis of the breathing muscles
- rare recovery reported
- almost always fatal once clinical signs begin
what does DFA stand for in rabies
direct fluorescent antibody
what are the 3 methods used to diagnose rabies
- direct fluorescent antibody
- negri bodies
- mouse inoculation
which test for rabies is the most used
DFA
how is a DFA performed for rabies
fresh brain tissue or a skin biopsy is obtained, this should be put in a refrigerator then a slide is prepared with fluorescent antibody and will glow if it is rabies positive
what are negri bodies
intracellular viral inclusions
what is the rabies confirmation test
mouse inoculation
what are the 2 vaccines that can be used for rabies
- modified live vaccine (not used in the us)
- inactivated or killed virus vaccine
what is the vaccination for dogs and cats for rabies
- initially vaccinate at 3 months and again 1 year later
- thereafter give booster vaccinations on an annual or triennial basis
- administer 1 mL. SQ or IM in right thigh
what is the vaccination for ferrets for rabies
- vaccinate at 3 months of age and then revaccinate annually
what is the vaccine that can be used for ferrets
RM IMRAB 3
what are 3 ways to control rabies in the cat and dog
- vaccination programs
- animal control shelters- management of strays
- leash laws
what can be done for the reduction of rabies amongst wildlife
- captive wild animals: should not be kept as pets, wild caught animals susceptible to rabies should be quarantined for a minimum of 180 days before exhibition in zoos
- oral vaccine baits are used by federal and state wildlife officials to control rabies during rabies epidemics in wildlife
how is an unvaccinated dog/cat bitten by a known rabid animal treated
- booster is given immediately and then quarantined for 6 months or 180 days
how is a vaccinated animal bitten by a known or suspected rabid animal treated
- a booster is given immediately and then they are quarantined for 45 days
what happens to strays, unwanted pets, wild carnivores that bite humans
they are euthanized and tested for rabies
what is the post -exposure prophylaxis with rabies
- wound care, aggressive washing
- passive and active immunotherapy
- vaccination within 24 hours of bite and then at 3, 7, 14, and 28 days
pre-exposure prophylaxis for humans
- humans at high risk
- three doses ( 0, 7, 21, or 28 days ID booster every 2 years)
- if exposed after immunization- two doses at 0 and 3 days
