203 Rabies Flashcards
True or false. Rabies has encephalitic and paralytic forms that progress to death
True.
Two genera of rabies that cause human disease
Lyssavirus and Vesciulovirus
True or false. Rabies is usually transmitted to humans by the bit of an infected animal
True.
True or false. Rabies may be acquired from skunks, foxes and raccoons.
True.
True or false. In North America, human disease is usually associated with transmission from bats
True
True or false. Transmission from nonbite like exposures is relatively uncommon.
True
incubation period of rabies
20-90 days, rare less than 1 day and more than 1 year
True or false. During the incubation period, the rabies virus is thought to be present at or close to the site of inoculation
True.
the rabies virus is known to bind where in the nerves
bind to nicotinic acetylcholine receptors on postsynpatic membranes at neuromuscular junctions
how does rabies virus spread inside the body
centripetally along the peripheral nerves towards the spinal cord or brainsteam via retrograde fast axonal transport
what is the axonal transport speed of rabies virus
250 mm per day with delays of 12 hrs at each synapse
prominently affected in rabies
neurons
where does rabies virus replicate
in acinar cells of the salivary glands and is secreted in the saliva of rabid animals that serve as vectors
True or false. There is no well documented evidence for hematogenous spread of rabies virus
True.
microglial nodules seen in rabies
Babes nodules
most characteristic pathologic finding in rabies
Negri bodies
Negri bodies vs babes nodules
negri bodies are cytocplasmic inclusions in brain neurons composed of rabies virus proteins and viral RNA while Babes nodules are mononuclear inflammation of microglial nodules
Where are Negri bodies in rabies observed
Prukinje cells of the cerebellum and in pyramidal neurons of the hippocampus and cortical and brainstem neurons
responsible for clinical disease in rabies
neuronal dysfunction
True or false. Negri bodies are no observed in all cases of rabies
True.
relates tot he aggressive behavrious of rabid animals
infection of serotonergic neurons of the brainstem
How does rabies present
atypical encephalitis with relative preservation of consciousness
phases in rabies infection
prodrome, acute neurologic, comatose and death
motor weakness in rabies
acute flaccid paralysis
the clinical feature of this phase is nonspecific manifestation like fever, malaise, headache, nausea, and vomiting
Prodrome
earliest specific neurologic symptoms of rabies which occur in 50-80% of patients
paresthesia, pain or pruritus near the site of exposure
two acute neurologic forms in humans
encephalitic (furious) form 80% and paralytic form 20%
signs of rabies encephalitis involving the brain stem
hydrophobia and aerophobia
what is hydrphobia
involuntary painful contraction of the diaphragm and accessory respiratory, laryngeal and pharyngeal muscles in response to swallowing liquids
mechanism of hydrophobia or aerophobia
exaggerated defense reflexes by the nucleus ambiguus that inhibit inspiratory neurons to protect the respiratory tract
autonomic dysfunction in rabies
hypersalivation, gooseflesh, cardiac arrythmia, and priapism
True or false. Paralytic rabies is seen in 20% of patient in which weakness predominates and cardinal features of hyperexcitability, hydrophobia and aerophobia are lacking
True.
Cause of coma or death in patient with rabies
brainstem dysfunction
from where are skin biopsy for rabies taken
cutaneous nerves at the base of hair follicles, samples are usually taken from hairy skin at the nape of the neck
True or false. Corneal impression smears are of low diagnostic yield and are not generally performed
True.
True or false. Presence of rabies virus specific neurtralizing antibodies in the CSF suggest rabies encephalitis, regardless of immunization
True.
diagnostically useful specimen in the diagnosis of rabies
serum, CSF, saliva, skin biopsy and brain tissue
a highly and specific test for detection of rabies virus RNA
RT PCR
True or false. There is no established treatment for rabies
True.
what is the prognosis of rabies
almost uniformly fatal
how long should healthy dogs, cats or ferrets be confined and observed
10 days
True or false. PEP for rabies is not necessary if the animal remains healthy
True.
True or false. If the the animal develops signs of rabies during the observation, it should be euthanized immediately
True.
Part of the animal sent for testing and viral isolation
head
True or false. In high risk exposure and in areas where canine rabies is endemic, rabies prophylaxis should be initiated without waiting for laboratory results
True.
Not later than how many days can RIG be administered after the first dose if not immediately available
no later than 7 days
can you give RIG 7 days after the first dose
theoretically endogenous antibodies are being produced and passive immunization is counterproductive
what is the dose of RIG
20 U/Kg, entire dose to site if anatomically feasible, if not then administered IM at a distant site
when can RIG administered all IM
if exposure involves mucous membrane
true or false. Pregnancy is a contraindication to rabies vaccine
False. Not contraindicated for immunization
Can glucocorticoids be given along with rabies vaccine?
No. it may interfere with the development of active immunity
when should purified inactivated rabies be given
immediately
timing of the purified inactivated rabies vaccine
Day 0, 3, 7, 14
alternative to RIG if not available and the dose
purified equine RIG can be used at dose of 40 U/ Kg
How to give pre exposure rabies vaccination
Day 0,7, 21 or 28
differentiate pre exposure versus post exposure vaccination
Post exposure: given 4x; Day 0,3,7,14 Pre exposure given 3x: Day 0, 7, 21
who are given pre exposure vaccination
travelers to endemic areas, occupational or recreational risk
who can be given booster rabies vaccination and how administered
previously immunized individual with booster dose given day 0 and day 3
True or false. RIG should be given to previously vaccinated persons
False. No need. Endogenous antibodies might already have developed
True or false. vesiculovirus can infect humans. It can cause flu like illness, conjunctivitis and small vesicular lesions
True.
True or false.Vesicular stomatitis virus lasts 3-6 days with complete recovery and rarely leads to encephalitis
True.
