Viro - Equine 1

isabellepjk's version from 2017-09-29 20:05

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 xmitted?Via blood-sucking insects, mainly the horse fly & the stable fly (MECHANICAL vector, not arbovirus). Can also be xmitted iatrogenically (contaminated needles, blood xfusion) & xmammary/xplacental (givin HIV to your baby, lame)
Is EIA an arbovirus?NO, insects act as mechanical vectors
Which seasons are most popular for xmission of EIA?Summer & Fall, when the horse/stable flies are most active
Is EIA xmammary or xplacental?BOTH (NO ABORTION)
Where does EIA like to persist in the horse?In the leukocytes
When is xmission of EIA more likely? Why? (NOT TALKING ABOUT SEASONS HERE)When the horse is showing signs of the dz, bc 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 EIASevere anemia & jaundice, blood stained feces, tachypnea & petechial hemorrhages of the mucosa. Can be FATAL! (up to 80% fatal) (Anemia Destroys blood → jaundice, use of clotting factors → petechia/hemorrhage. Bleeding → poop blood. Fast breathing bc blood is crap & so not much O2 = eventual death. 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 persistent fever, cachexia, anemia & ventral edema
What are the cells EIA usually infects? What does this often lead to?Infxn of macrophages & lymphocytes = cell-associated viremia
How does EIA affect the blood?Anemia may result from bone marrow suppression, increased clearance of RBC or autoimmune destruction. Might also have hemorrhages from thrombocytopenia
How does the immune system react to/fight EIA, how effective is it?Vasculitis & glomerulonephritis is mediated by immune complexes (immunopathology - Type 3 Hypersensativity rxn) (use Coggins to detect the cog-shaped immune complexes)
What might be a reason there are periods of reoccurrence in EIA?During reoccurrence significant genomic variations, including deletions have been mapped to the principal neutralizing domain of the envelope protein (gp90) (so, in essence, it can mutate & escape the immune system)
What are 3 tests you'd use to diagnose EIA?(1) SEROLOGICAL (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? 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 & in certain situations w/ animals)?Good to detect the PROVIRAL DNA. Can use for confirming other tests, & is often used to test foals birthed from infected mothers & 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?NOPE
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 & ABORTION in newly infected mares (lots of arteries going to the placenta & the lungs!! baby gotta breathe through mom, yo)
What is morbidity & mortality like for EVA?High morbidity & Low mortality
How is EVA xmitted?Shed in the resp secretions of infected horses, stallions can be long term shedders & cause venereal spread. Also can be spread by fomites (UNUSUAL BC ENVELOPED) & the fetal fluids of aborted foals (makes sense, bc is mainly a resp+abortion dz, so spread via resp & repro ways)
How resistant is EVA in the environment?It is VERY RESISTANT! EVEN THO IT IS ENVELOPED!!! (Arteries dont degrade easily)
Is EVA xmammary, xplacental, neither, or both?Xplacental!! 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 & intestinal necrosis. There is also edema in the limbs, ventral abdomen(<--CS of EIA also!), scrotum & prepuce. There may also be abdominal pain (colic)& 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 & damage BVs (hence, arteritis). Might see nasal mucosa petechiation (respiratory dz w/ artery damage → nose petechiation) leaky endothelial = edema
Where do you commonly see edema in EVA?Palpebrae, limbs, ventral abdomen, scrotum, prepuce. (Low places, & places w/ fragile skin)
How does the virus start to infect the body & what is its pathogenesis?Virus inhaled → infects alveolar macrophages & moves to the lymphnodes this way. Then from there moves to the blood stream to cause the viremia & 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 & Equine Influenza). Samples to take are nasopharyngeal swabs, blood, urine & 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 & 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 & then your baby)
How do you control EVA? How is it diff for stallions, mares, & foals?THERE IS A VX!
(1) Stallions: should be vx 60 days (2 MONTHS) before breeding season & 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 at 6-8mo. After maternal Abs decline
What should you do during an outbreak of EVA?Restrict movement, isolate/quarantine convalescent horses, keep good hygiene, perform laboratory surveillance & use separate handlers for affected & non-affected horses
Is EVA zoonotic?NO
Is this a systemic dz or does it affect a certain body system?Systemic

Equine Encephalitis

Question Answer
Etiological agent? DNA or RNA? Enveloped or naked?Togaviridae, RNA, enveloped (Crazy men in togas)
Is equine encephalitis zoonotic?YES (remember, stupid is contagious)
Is equine encephalitis a systemic dz, or does it deal w/ a particular body system?CNS
How is equine encephalitis xmitted?Via insect VECTORS → MOSQUITOS (ARBOVIRUS) (mosquitos are as annoying as encephalitis, what a perfect match)
What animal is the reservoir for EQ Encephalitis, & what happens inside of them?BIRDS are the reservoir & they AMPLIFY the virus
Who are the DEAD END HOSTS for equine encephalitis?Horses & humans
What are the clinical signs of equine encephalitis?Neuro signs (depression, wide stance w/ low head, paralysis) & encephalitis (irritation & 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 sequelae after an animal recovers?Neurological sequelae, like dullness & dementia (they derp for life)
Major sign of encephalitis she emphasized in classHead pressing against corner of stall
How does EQ Encephalitis get xmitted & what is necessary for this xmisson to be successful?ARBOVIRUS means xmitted by insect vector (mosquito) but a 2nd viremia meaning there is a high titer is important for the xmission & the CNS invasion which causes the encephalitis. In this case it only applies to birds! Horse 2nd viremia titer is not high enough for vector transmission (this is why horses are not a resevior)
Important part of Pathogenesis?2nd viremia (high titer) is important for transmission & CNS invasion which causes enchephalities BUT its still not enough for vector transmission from horses
What are the DDx for equine encephalitis?Rabies, Equine Herpesvirus 1 (EHV-1 Equine Abortion) & West Nile Virus
How would you Dx equine encephalitis? (3)IgM capture ELISA (M is for MASSIVLY STUPID bc of the encephalitis) & confirmation can be done by virus seroneutralization. If the horse is dead, you can do a post-mortem RT-PCR from brain tissue
Is there a vx?YES an inactivated vax for horses can be given annually (VACCINE IN THE MEMBRANE, VACCINE FOR THE BRAIN!)
How can you control equine encephalitis?VX & mosquito control (VACCINE FOR THE BRAIN!)
What special thing can Eastern Equine Encephalitis do??It can also infect broilers (chickens)
What is the only state in the USA that has all 3 Equine Encephalitis Dz's?TEXAS

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 xmitted?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 & 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 & a very small proportion may die (so...not as severe as encephalitis)
How can you dx West Nile?RT-PCR, IHC, IF, virus isolation, serology (IgM ELISA, neutralization, complement fixation) (like all the things)
Is there a vx?Yes (Recombinant for horses; Inactivated, Recombinant & DNA for humans)
How can you control West Nile?Vx & 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 of the Orthomyxoviridae family. RNA, SEGMENTED, enveloped
Unique attributes of the equine influenza virus structure?Orthomyxo, genome is SEGMENTED & they have large peplomers of 2 kinds: rod-shaped HA (hemagglutinin) & mushroom shape NA (neuroaminidase)
What about equine influenza contributes to its virulence?Defective interfering particles & genetic ressortment occur frequently (segmented genome)
Where does equine influenza occur geographically?Worldwide
Is equine influenza zoonotic?No
Is equine influenza a systemic dz, or is it related to a particular body system?RESPIRATORY
What is the rate of xmission of equine influenza among horses?Rapid (it’s the flu) Very high rate (~100%) of xmission amoung horses and short incubation time (1-2 days)
In what situations is there mortality from equine influenzaRare, 2° infxns might lead to BRONCHOPNEUMONIA but mortalitiy is rare; 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 & lower respiratory tract, inflammation leads to nasal serous discharge
Clinical signs?Fever >39°C, Dry hacking cough (bronchopneumonia), conjuctivitis, Serous nasal discharge that becomes mucopurulent, 2° infxns, depression, reluctance to eat or drink for several days & guttural pouch infxns can also happen, but they usually recover in 2-3 weeks
What are important DDx's for this?Needs to be differentiated from Equine Herpesvirus 1 (EHV-1)(abortion) & 4 (rhinopneumonitis), Equine Adenovirus & 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) & you know they are replicating if you see Hemagglutination
How can you dx EI? (3)(1) Virus isolation from early stage nasal mucus or lung material
(2) Hemagglutination (Replication demonstation or inhibition using a subtype-specific reference antisera)
(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 & 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 w/ 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 dz in foals weanlings & 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 infxn
Clinical signs?Profuse serous nasal discharge which later becomes mucopurulent (Similar to Vesicular Stomatitis!)
How common are the severe vs the mild & subclinical?Mild & subclinical are common
What factors might lead to complications/ what are these complications?Crowding, poor hygiene & stress can lead to 2° infxns → 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