Lecture 15: Rabies and vesicular stomatitis Flashcards
How do you dx rabies
FA impression smears of midbrain, cerebellum and hippocampus
what is geographic distribution of rabies virus vs bat lyssaviruses
- Rabies virus- worldwide besides Australia and Antarctica
- Bat lyssaviruses- Europe, Australia
99% of human cases of rabies are transmitted by __
dogs
what is pathogenesis of rabies
- Peripheral exposure- bit, contact with body fluids
- Infection of peripheral nerve endings
- Centripetal phase- retrograde axonal transport to dorsal ganglion
- Dissemination throughout CNS
- Centrifugal phase- spreads to salivary glands, eye, skin
what is incubation period for rabies
3-12wks
what factors affect incubation period
- Host species
- Virus strain
- Dose exposure
- Exposure site
what species are rarely susceptible to rabies
opossum, small rodents
how does exposure site affect incubation period for rabies
axonal transport has rate limit- the longer the axon the longer it takes to reach CNS
1yr cow presents with hypersalivation, dysphagia and progresses to stargazing, ataxia, difficulty rising. What are you concerned about
rabies
what are these and what virus are they indicative of
Negri bodies- rabies
how do you dx rabies in animal that bite
- Euthanize and FA testing
- 10 day isolation- if actively shedding rabies at time of bite then will die within 10 days
how do you prevent rabies
- Killed vaccines single dose at 14wks, 1yr, q1 or 3yrs
- Oral baits for wildlife
what is treatment for animal bitten by suspected rabid animal who has hx of rabies vaccine
booster and outpatient monitor 45d
what is treatment for animal bitten by suspected rabid animal that is not vaccinated
- Euthanize if biting animal tests positive
- Long term inpatient monitoring (4months) if biting animal was not tested followed by vaccination
how long do ferrets have to undergo inpatient monitoring if bitten by suspected rabid animal but unable to test biting animal
6 months
why 4-6 months for inpatient monitoring of suspected rabies bite
4-6 months is upper limit of incubation period
how long is quarantine period for animal that has bitten someone
10 days
what are the vectors for rabies transmission in U.S. and worldwide
US- bats, skunks, raccoons
Outside US- dogs
horse presents with these lesions what is top differential
vesicular stomatitis
how is vesicular stomatitis virus transmitted
- Direct contact
- Biological vector-culicoides
what are the two major serogroups of vesicular stomatitis virus
Indiana and New Jersey
ruled out FMD what likely caused these lesions
vesicular stomatitis
what are some clinical signs of vesicular stomatitis virus
- Vesicular lesions of tongue and oral cavity
- Hypersalivation and secondary infections
- Coronary band lesions-lameness
what does a positive titer for vesicular stomatitis mean
could be prior exposure, do paired serology titer few weeks later to confirm
how do you dx vesicular stomatitis
serum, vesicular fluid, serology, virus isolation, rt-PCR
What is tx for vesicular stomatitis virus
- Palliative- secondary infections
- quarantine 14-30 day after last suspected case
why is there no commercial vaccine for vesicular stomatitis virus
makes dx difficult- hard to differentiate between infected vs vaccinated
how does vesicular stomatitis outbreak behave in norther vs southern climates
northern- rare outbreaks, more severe
Southern- yearly cases, less severe
how is VSV transmitted and how does this help explain its cyclical appearance
culicoides midges which are only present seasonally. Often large parts of country are exposed and develop herd immunity for 5+years
what procedures must be taken when VSV is suspected and where are samples sent for dx
notify state/regional USDA vet. Samples sent to USDA labs in either Iowa or plum island
