Virology- Viral Diseases of Horses 1

kelseyfmeyer's version from 2015-04-16 19:11

Equine infectious anemia

Question Answer
etiological agent? DNA or RNA? Enveloped or naked?Retroviridae, RNA, enveloped
EIA is aka?swamp fever (she said it was the "HIV of equine") (weird...HIV swamp? sounds like a great family trip)
where does EIA occur geographically?worldwide
how is EIA transmitted?via blood-sucking insects, mainly the horse fly and the stable fly (MECHANICAL vector, not arbovirus). Can also be transmitted iatrogenically, (contaminated needles, blood xfusion), AND transmammry/transplacental (givin HIV to your baby, lame)
is EIA a arbovirus?NO, insects act as mechanical vectors
which seasons are most popular for transition of EIA?summer and fall, when the horse/stable fly is most active
is EIA transmammary or transplacental?BOTH (NO ABORTION)
where does EIA like to persist in the horse?in the leukocytes
when is transmission of EIA more likely? Why? (NOT TALKING ABOUT SEASONS HERE)when the horse is showing signs of the dz, because they have a higher viral titer than a horse which isnt showing signs
what are the 4 stages of EIA?acute, subacute, recovered, chronic
describe the clinical signs of the acute stage of EIAthere is severe anemia and jaundice, blood stained feces, tachypnea, and petechial hemorrhages of the mucosa. This can be FATAL! (up to 80% of cases) (so...anemia crap. Destroy blood--> jaundice. Destroy blood--> use clotting stuff up--> petechia/hemorrhage. Bleeding--> poop blood. Fast breathing because blood is crap and so not much O2. Dead because no blood. Blood HIV sucks)
what is the main clinical sign of the subacute phase of EIA?the appearance of neutralizing antibodies!! (their presence is prolly why it isnt acute any more)
what should you know about horses in the recovered stage of EIA?can perform well but may have recurrent episodes
what are the clinical signs like for the chronic form of EIA?can range from mild signs to episodic or persistant fever, cachexia, anemia and ventral edema
what are the cells EIA usually infects? what does this often lead to?Infection of macrophages and lymphocytes, cell-associated viremia
how does EIA affect the blood?anemia may be result of bone marrow suppression, increased clearance of RBC or autoimmune destruction. Might also have hemorrhages from thrombocytopenia
how does the immune system react to or fight EIA, what are the effects/ how effective is it?Vasculitis and glomerulonephritis is mediated by immune complexes (immunopathology) (use coggins to detect the cog-shaped immune complexes)
what might be a reason there are periods of reoccurance in EIA?During reoccurence significant genomic variations, including deletions have been mapped to the principal neutralizing domain of the envelope protein (gp90) (so, in essence, it can mutate and escape the immune system)
what are three tests you'd use to diagnose EIA?(1) SEROLOGICAL!! (it is retro!) (2) COGGINS (immunodiffusion) can be used, but can give false negs in early stages (3) PCR is used to detect proviral DNA (good for confirmation)
is it coombs or coggins you use? and what is something you need to know if you use this test?COGGINS! must know that you can have false negs in early stages (not enough Abs made yet) (horse HIV--> turning the cogs on the death machine of life)
why would you want to use PCR (virus specific, and in certian situations with animals)good to detect the PROVIRAL DNA. Can use for confirming other tests, and is often used to test foals birthed from infected mothers, and for control of seropositive animals
is there a vx?no! (retrovirus!)
what is control/control policies like for EIA?no vx, can only isolate positive animals, however it is not compulsory to destroy a positive horse. Only decent control is trying to limit/destroy insect vector populations. (there are horse HIV herds. weird.)
is EIA zoonotic?no
is this systemic or is it pertaining to a specific body system?systemic

Equine viral arteritis (EVA)

Question Answer
etiological agent? DNA or RNA? Enveloped or naked?Arterivirus, RNA, enveloped (enveloped but remember it's resistant)
where does EVA occur geographically?worldwide
what are the two main things EVA causes?mild respiratory dz and ABORTION (lots of arteries going to the placenta and the lungs!! baby gotta breathe through mom, yo)
what is morbidity and mortality like for EVA?high morbidity and low mortality
how is EVA transmitted?shed in the resp secretions of infected horses, stallions can be long term shedders and cause venereal spread. Also can be spread by fomtes (UNUSUAL BC ENVELOPED), and the fetal fluids of aborted foals (makes sense, bc is mainly a resp+abortion dz, so spread via resp and repro ways)
how resistant is EVA in the environment?it is VERY RESISTANT! EVEN THO IT IS ENVELOPED!!! (Arteries dont degrade easily)
is EVA transmammary, transplacental, neither, or both?Transplacental!! which is why it can cause abortion
what are the clinical signs of EVA?leukopenia, serous nasal discharge, conjunctivitis, purulent ocular discharge, palpebral edema(idk dude, there are delicate arteries in the eyelids?), photophobia (wut? retinal artery damage maybe?), skin rash, nasal mucosal petechiation may be observed. In severe cases, foals have died from pneumonia and intestinal necrosis. There is also edema in the limbs, ventral abdomen, scrotum, and prepuce. There may also be abdominal pain and diarrhea.
when do most abortions occur from EVA?between 5-10mo of gestation (basically the last part)
how does EVA affect the blood? blood vessels?leukopenia(starts by infecting alveolar macros, remember?), there will be viremia--> virus will replicate in the endothelial cells and damage BVs (hence, arteritis). might see nasal mucosa petechiation (respiratory dz with artery damage--> nose petechiation)
where do you commonly see edema in EVA?palpebrae, limbs, ventral abdomen, scrotum, prepuce. (low places, and places with fragile skin)
how does the virus start to infect the body, and what is its pathogenesis?virus inhaled--> infects alveolar macrophages and moves to the lymphnodes this way. Then from there moves to the blood stream to cause the viremia and endothelial damage
Dx--> must differentiate EVA from what? what SAMPLES would you take to try to dx it?must differentiate from other equine resp dzs (equine herpes and equine influenza). Samples to take are nasopharyngeal swabs, blood, urine and aborted fetal tissues
what is the dx method of choice? what other method can you use?METHOD OF CHOICE is RT-PCR but you can also use Ab ELISA (ARTERI and RTPCR.)
are there vx?YES
who are the shedders which can continue to shed for weeks to years?stallions. look out for their semen, it will kill your arteries, and then your baby
how do you control EVA? how is it diff for stallions, mares, and foals?THERE IS A VX! so... (1) stallions: should be vx 60 days (ONE MONTH) before breeding season, and infected stallions should only be bred to seropositive or vaccinated mares. (2) if the mare is going to be bred to a seropositive male, vxs should be done at least 3wk in advance. ALSO mares should NOT BE VX DURING LAST 2 MO GESTATION! (3) foals can be vx 6-8mo after maternal Abs decline
what should you do during an outbreak of EVA?restrict movement, isolate and later quarantine convalescent horses, keep good hygiene and separate handlers for affected and non affected horses and perform laboratory surveillance
is EVA zoonotic?NO
is this a systemic disease or does it affect a certian body system?systemic

Equine encephalitis

Question Answer
etiological agent? DNA or RNA? Enveloped or naked?Togaviridae, RNA, enveloped. (Mentally crazy men wearing togas)
is equine encephalitis zoonotic?YES (remember that stupid is contagious)
is equine encephalitis a systemic dz, or does it deal with a particular body system?CNS
how is equine encephalitis transmitted?Via insect VECTORS--> MOSQUITOS (ARBOVIRUS) (mosquitos are as annoying as encephalitis, what a perfect match)
what animal is the reservoir for EEitis, and what happens inside of them?BIRDS are the reservoir and they AMPLIFY the virus
who are the DEAD END HOSTS for equine encephalitis?horses and humans!!
what are the clinical signs of equine encephalitis?neuro signs (depression, wide stance with low head, paralysis) and encephalitis (irritation and swelling (inflammation) of the brain)--> signs of encephalitis include impaired vision, photophobia, impaired ability to swallow, circling, grinding teeth, HEAD PRESSING AGAINST CORNER OF STALL
what are the sequale after an animal recovers?neurological sequale, like dullness and dementia (they are a derp for life)
major sign of encephalitis she emphasized in classhead pressing against corner of stall
how does EEitis get transmitted, and what is necessary for this transition to be successful?ARBOVIRUS means transmitted by insect vector (mosquito) but a 2nd viremia meaning there is a high titer is important for the transmission and the CNS invasion which causes the encephalitis. (IE, the high titer is needed for the mosquitos to pick it up) (You know what's as annoying as encephalitis? mosquitos)
what are the differential diagnoses for equine encephalitis?rabies, equine herpesvirus 1(equine abortion) and west nile virus
how would you diagnose equine encephalitis? (3)IgM capture ELISA (M is for MASSIVLY STUPID because of the encephalitis), and confirmation can be done by virus seroneutralization. If the horse is dead, you can do a post-mortem RT-PCR from brain tissue
how can you control equine encephalitis?VX and also mosquito control (VACCINE FOR THE BRAIN! )

West Nile encephalitis

Question Answer
etiological agent? DNA or RNA? Enveloped or naked?FLAVIVIRIDAE, RNA, enveloped (the nile river has a particular FLAVor)
is west nile encephalitis zoonotic?YES (remember the news blowing up over this?)
how is west nile encephalitis transmitted?ARBOVIRUS! MOSQUITO! (just like encephalitis again)
what are the regular hosts of west nile? what are the dead-end hosts?regular host is birds, horses and humans are dead end hosts (just like encephalitis)
what are the clinical signs of west nile?In horses most cases are asymptomatic but a few exhibit neurologic signs and a very small proportion may die (so...not as severe as encephalitis)
how can you diagnose west nile?RT-PCR, IHC, IF, virus isolation, serology (IgM ELISA, neutralization, complement fixation) (like all the things)
is there a vx?yes
how can you control west nile?vx, and insect vector control (just like encephalitis)
is this a systemic dz, or does it pertain to a specific body system?CNS

Equine influenza

Question Answer
etiological agent? DNA or RNA? Enveloped or naked?Influenzavirus A genus of the Orthomyxoviridae family. RNA, SEGMENTED, enveloped.
unique attributes of the equine influenza virus structure?orthomyxo, genome is SEGMENTED, and they have large peplomers of 2 kinds: rod-shaped HA (hemagglutinin) and mushroom shape NA (neuroaminidase)
what about equine influenza contributes to its virulence?Defective interfering particles and genetic reassortment occur frequently (segmented genome)
where does equine influenza occur geographically?worldwide
is equine influenza zoonotic?no
is equine influenza a systemic disease, or is it related to a particular body system?RESPIRATORY
what is the rate of transmission of equine influenza among horses?rapid (its the flu)
in what situations is there mortality from equine influenzarare, secondary infections might lead to BRONCHOPNEUMONIA. Also a prolonged fever can lead to ABORTION
that is the pathogenesis of EI? (where does virus replicate, what results does this lead to?)virus replicates in the epithelial cells of the upper and lower respiratory tract, inflammation leads to nasal serous discharge.
clinical signs?serous nasal discharge, Secondary infections, conjuntivitis, bronchopneumonia and gutteral pouch mycosis can also happen
what are important ddx's for this?needs to be differentiated from equine herpesvirus 1(aboriton-->bc this can cause abortion)& 4(rhinopneumonitis), equine adenovirus, and rhinoviruses
what samples are collected to perform viral isolation? how do you know they are replicating?Samples: nasal mucus if early stage, lung material if post mortem. (embryonated egg via amniotic or allantoid route or in cell culture.) and you know if they are replicating if you see hemagglutination
how can you dx EI? (3)(1) virus isolation (see other card) (2) Hemagglutination (3) retrospective serological testing
is there a vx?YES (flu shots! yay!)
how do you control EI? what if there is an outbreak?can use VX!! if outbreak, isolate horses and then quarantine(4wk). disinfect premise

Equine rhinopneumonitis

Question Answer
etiological agent? DNA or RNA? Enveloped or Naked?Equine herpesvirus **4** (EHV-4). DNA, enveloped. (Rhino with 4 horns hanging out next to a sneezing horse)
microscopic give-away?intranuclear inclusion bodies (herpes)
how does Equine rhinopneumonitis/EHV4 affect horses, depending on AGE?acute respiratory disease in foals weanlings and yearlings. In adult horses, reactivation of latent virus (might be responsible for episodes of febrile resp dz)
what is shedding like for ER?HERPES! There is inapparent viral shedding after reactivation in adult horses may be the source of infection.
clinical signs?profuse serous nasal discharge which later becomes mucopurulent
how common are the severe vs the mild and subclinical?mild and subclinical are common
what factors might lead to complications/ what are these complications?crowding, poor hygiene and stress can lead to secondary infections-->pneumonia--> death
how would you diagnose ER?PCR, IF detection of viral antigens, serologic testing as well as virus isolation, are used
is there a vx?YES
is this systemic or does it infect a body system?RESP

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