Term
| What is the layman's term for Equine Infectious Anemia? |
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Definition
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Term
| Which species are affected by Swamp Fever? |
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Definition
| -horses, donkeys, and mules worldwide |
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Term
| Why is EIA nicknamed "Swampe Fever"? |
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Definition
| -occurs predominantly in humid, ow-lying areas, the habitat of the arthropod vector |
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Term
| True or False: Once infected, horses remain persistent carriers of the EIA virus. |
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Definition
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Term
| EIA belong to which viral family? Which genus? |
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Definition
-Family = Retroviridae
-genus = Lentivirus |
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Term
| What are the important viral proteins of EIA? |
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Definition
-viral glycoprotein gp60
-majpr group-specific core protein p26 |
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Term
| What is the primary difference b/n serotypes of EIA? |
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Definition
| -differences in the amino acid sequence of their gp90 |
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Term
| Which animal is the only recognized reservoir of EIA virus in nature? |
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Definition
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Term
| EIA virus can be detected in the ___(cell type)___ of all infected horses as a ______. |
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Definition
-macrophages/monocytes
-provirus |
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Term
| Is there a viremia associated with EIA? |
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Definition
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Term
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Definition
| -transfeer of viral infected blood cells via Tabanids (stable flies, deer flies) |
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Term
| What season is the peak time of EIA transmission? |
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Definition
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Term
| Other than the primary EIA transmission via Tabanids, how else can it be transmitted? |
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Definition
-blood transfusion
-iatrogenic transmission |
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Term
| What is the incubation period of EIA? |
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Definition
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Term
| What are the clinical signs of acute EIAinfeciton? |
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Definition
| -high fever, anorexia, ataxia, profound weakness, thrombocytopenia = petechial hemorrhages, rapid weight loss, edema on abdomen and legs |
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Term
| How long do the clinical signs of acute EIA last? Then what happens? |
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Definition
-about a week
-either die or recover and become a persistent carrier |
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Term
| When does recurrent fever happen in EIA cases? |
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Definition
| -weeks to months after the initial acute attach |
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Term
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Definition
| -recurrent attacks of fever |
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Term
| Describe the signs of the chronic recurrent form of EIA? |
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Definition
| -fever, anemia, weakness (wobbly, tired), emaciation, ventral edema, thrombocytopenia, hypergammaglobulinemia |
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Term
| What are the two possible outcomes of a recurrent bout of EIA? Do they recur? |
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Definition
-die or recover
-can recur but most remain healthy for the rest of their lives without undergoing clinically noticeable recurrent attacks |
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Term
| Where does EIA replicate in the body? |
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Definition
| -resident macrophages in the liver, spleen, lymph nodes, etc |
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Term
| Many of the clinical signs of EIA attributable to immunologically? |
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Definition
| -release of pro-inflammatory cytokines: TNF-alpha, IL-1, IL-6 by infected macrophages |
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Term
| When the circulating AB to ______ appears during an EIA infection, the virus stops replicating, the clinical signs subside, and the EIA virus disappears from the blood for a variable period of time. |
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Definition
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Term
| So if EIA virus disappears from the blood while circulating Ab to gp90 appear, are they still infected? |
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Definition
-YES
-EIA remains as a provirus in resident macrophages |
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Term
| What makes recurrent attacks possible? |
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Definition
| -in between recurrent attacks, the virus continues to replicate and accumulate point mutations in the gene encoding gp90 (constant antigenic drift) & when the mutations result in the formation of a gp90 that is nor longer recognized by the circulating NA, the new antigenically-changed-mutant will start to replicate to high levels, infect other macrophages, and result virus replication and viremia causing a recurrent attack |
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Term
| What happens during a recurrent attack of EIA? |
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Definition
| -viral proteins that attach to circulating RBC are released into the blood, these RBCs fix complement on their surface and are removed from circulation by erythrophagocytosis in the liver and spleen leading to anemia |
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Term
| True or False: In a recurrent attack of EIA, anemai is due to primarily to complement-mediated eryhtrophagocytosis, although some intravascular hemolysis is seen. |
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Definition
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Term
| In the case of EIA, only the ______ changes antigenically during recurrent attacks. |
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Definition
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Term
| What causes the hypergammaglobulinemia during recurrent episodes of EIA? |
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Definition
| -due to Ab production caused by clonal expansion of memory/plasma cells specific p26 and other viral proteins that have not changed antigenically |
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Term
| What leads to immune-complex mediated glomerulonephritis in EIA? |
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Definition
| -Ag:Ab complexes that are formed in the blood are deposited in the kidney |
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Term
| Describe the clinical pathology of EIA. |
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Definition
| -severe thrombocytopenia, severe anemia, erythrophaocytosis, hypergammaglobulinemia |
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Term
| What are the pathological lesions we see at necropsy of an EIA case? |
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Definition
| -hemorrhage, splenomegaly, emaciation, anemia, enlarged reddish-brown liber, hematopoiesis |
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Term
| Can EIA be detected in a latently infected animal? |
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Definition
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Term
| What is the primary difference regarding the results of a PCR and RT-PCR test for EIA? |
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Definition
-PCR cannot differentiate macrophages producing infectious particles from those that are latently infected
-RT-PCR will identify macrophages with replicating virus |
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Term
| Which two tests that the State recognizes for the diagnosis of EIA? |
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Definition
| -compettitive-ELISA and the Agar Gel Immunodiffusion test (AGID) |
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Term
| What doe the c-ELISA and AGID test detect? Which is most commonly performed? |
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Definition
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Term
| What is the layman's term for the EIA AGID test? |
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Definition
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Term
| Is the c-ELISA or Coggins test more sensitive for EIA? |
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Definition
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Term
| Which test for EIA is the definitive final test? |
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Definition
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Term
| What is the disadvantage to prophylactically testing horses for EIA? |
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Definition
| -animals in the acute phase of infection may be seronegative |
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Term
| Foals that are born of EIA-infected dams will test seropositive until _____ months of age if they are not also infected. What will they test then? |
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Definition
-6 months
-Then they will test seronegative if they are truly negative |
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Term
| Most animals will develop persisitant circulaitng Ab within ___ days of EIA infection. Some will test ELISA-positive by ___ days post infection and AGID-positive by ___ days post infection. |
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Definition
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Term
| True or False: EIA is a notifiable disease. |
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Definition
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Term
| What kind(s) of vaccine(s) are/is available for EIA in horses? |
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Definition
| -no vaccine is avvailable, thus must test all horses by ELISA prior to moving them out of state |
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Term
| What is the other name for Equine Herpesvirus Type-I? |
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Definition
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Term
| What is the most important cause of abortion in mares? How else does it present? |
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Definition
-EHV-1
-resp dz in younger horses and neuro dz in adult horses |
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Term
| EHV-1 belongs to which virus family? What kind of herpesvirus is it? |
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Definition
-family = Herpesviridae
-alphaherpesvirus |
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Term
| What other virus is EHV-1 closely related to? What is its other name? |
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Definition
-EHV-4
-equine rhinopneumonitis virus |
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Term
| It is estimated that >___% of horses worldwide are naturally infected with EHV-1. |
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Definition
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Term
| What is the incubation of EHV-1? Does it change with the relevant form? |
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Definition
-about 7 days
-yes, longer for EHV-1 associated aboriton and myeloencephalopathy |
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Term
| How is EHV-1 transmitted? |
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Definition
-inhalation of infected droplets during respiratory diseases
-ingestion/mucosal ocntact with infected material such as aborted fetuses |
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Term
| What is the major cause of EHV-1 recrudescnence? Examples? |
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Definition
-stress
-ex: pregnancy, foal-at-foot, weaning, horse show events |
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Term
| What form of EHV-1 is seen in older horses? In which environments does it predominantly occur? |
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Definition
-myeloencephalopathy
-where horses congregate: show events, race tracks, vet hosptial |
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Term
| EHV-1 is the most important cause of abortions in mares. At which point of pregnancy does it occur? |
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Definition
| -after the 6th month of pregnancy |
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Term
| Are EHV-1 abortions sporadic or storm-like? |
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Definition
| -usually sporadic but can cause abortion storms |
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Term
| What else happens on the ranch concurrently with abortions due to EHV-1? |
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Definition
| -respiratory disease outbreaks in foals a few weeks preceding the outbreak of aboriton in mares |
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Term
| Do mares aborting due to EHV-1 show clinical signs of illness or not? |
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Definition
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Term
| How well do mares that aborted due to EHV-1 recover? |
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Definition
| -well, no retained placenta or infection |
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Term
| During what 3 instances do you see EHV-1 myeloencephalopathy? |
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Definition
1) during and following abortion storms
2) 1-3 months after foaling3) a few weeks after a respiratory disease outbreak in mares and foals |
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Term
| What are the clinical signs of EHV-1 myeloencephalopathy? |
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Definition
| -incoordination, ataxia, posterior paresis, recumbency, sometimes death |
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Term
| How do we treat EHV-1 myeloencephalopathy? |
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Definition
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Term
| The myeloencephalitis form of EHV-2 is caused by the neuropathogenic EHV-1. How can this be differentiated from respiratory virus? What other forms of EHV-1 can cause CNS disease and how? |
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Definition
-mutation in the DNA polymerase gene
-respiratory EHV-1 can cause CNS disease and the neuropathogenic virus is transmitted via the repsiratory route and can cause severe pneumonia in young foals |
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Term
| True or False: EHV-1 is a repsiratory virus and will replicate in upper respiratory tract and lungs, often with no resultant respiratory disease. |
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Definition
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Term
| How does EHV-1 spread through the body? |
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Definition
| -virus is picked up by alveolar macro9phages in the lung, brought to the lymph nodes, infect lymphocyte, and the infected lympocytes carry the virus throughout the obdy |
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Term
| What happens if a mare is infected with EHV-1 while pregnant? |
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Definition
| -EHV-1 is carried to the placenta in infeted lymphocytes, invades and replicates in the placenta, and infects and kills the fetus |
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Term
| EHV-1 myeloencephalopathy has been associated with ______ and ______ of blood vessels (arterioles) in the spinal cord and CNS. |
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Definition
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Term
| All abortion in mares should be considered as caused by ______. |
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Definition
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Term
| What is found at necropsy of EHV--1? |
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Definition
| -aborted fetuses show icterus, petechial hemorrhages on mucous membranes, and FOCAL DISSEMINATED HEPATIC NECROSIS |
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Term
| What are the most consistent lesions in the aborted fetus due to EHV-1 infection? |
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Definition
| -multiple focal areas of necrosis in the liver with intranuclear inclusions in the ifnected cells |
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Term
| What is the predominant lesion in EHV-1 myealoencephalopathy cases? |
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Definition
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Term
| How do we differentaite b/n neuropathogenic EHV-1 and respiratory EHV-1 in the lab? |
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Definition
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Term
| Are FA and IHC good for EHV-1 detection? What samples do we submit? |
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Definition
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Term
| What is the downside of using serology to detect EHV-1? How do we get around this? |
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Definition
-VNT is unable to distinguish b/n EHV-1 and EHV-4 ifnections
-a specific c-ELISAcan distinguish b/n EHV-1 and EHV-4 |
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Term
| IS seroconverison a diagnostic test for EHV-1? |
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Definition
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Term
| Myeloencephalotpathy due to EHV-1 is thought to occur only in the presence of what? |
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Definition
| -circulating AB (hence serology is not particularly useful) |
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Term
| What two strains of EHV-1 are we concerned about? |
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Definition
| -neuropathogenic and abortogenic strains |
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Term
| What do we use to treat EHV-1? |
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Definition
-Acyclovir
-strict isolation, quarantine, and disinfection |
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Term
| What are the two forms of EHV-1 vaccines available? Describe them |
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Definition
-MLV given IM: not very immunogenic and does not protect fully against aboritons
-Inactivated vaccines: provide good immunity but must be given frequently |
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Term
| When should pregant mares be vaccinated for EHV-1? |
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Definition
| -5th, 7th, and 9th months of pregnancy |
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Term
| What is the other ame for Equine Viral Arteritis (EVA)? |
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Definition
| -Epizootic cellulitis - Pinkeye |
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Term
| Equine arteritis virus (EVA) is the causative agent of ________ in horses that occurs worldwide. Characterize this disease. |
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Definition
-equine viral arteritis
-respiratory and reproductive disease |
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Term
| Are the majority of EVA infections cliical or subclinical? In which specific horses most commonly? |
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Definition
-subclinical
-standardbreds |
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Term
| Which viral family and genus does EVA belong to? |
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Definition
-Family = Arteriviridae
-Genus = arterivirus |
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Term
| Characterize the size and genome of EVA. |
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Definition
| -small neveloped RNA virus |
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Term
| What percentage of Standardbreds are seropositive for EVA in the US? Compare this to Thoroughbreds. |
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Definition
-70-90%
-only 1-3% of thoroughbreds |
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Term
| What are the 3 methods by which EVA can be transmitted? |
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Definition
-aerosol transmission during outbreaks of respiratory disease
- venereally through infected semen
-mucosal contact with infected tissues such as aborted fetuses, placental membrane, and secretions |
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Term
| What is the most important means of EVA transmission on breeding farms? |
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Definition
| -venereally through infected semen |
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Term
| How long do stallions shed EVA in semen post-infection? |
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Definition
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Term
| True or False: Once a mare is venereally infected with EVA, it can spread the virus to other mares via aerosol transmission. |
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Definition
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Term
| What is the incubation period for EVA? |
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Definition
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Term
| What 6 things characterize EVA? |
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Definition
-fever lasting about 1 week
-upper respiratory infection with serous to mucoid nasal and ocular discharges
-severe conjuncitivits with accompanying photophobia
-supraorbital/periorbital edema
-edema of lower legs, genitalia (scrotum, prepuce), mammary glands, and abdomen
-change in gait: ataxia and/or with stiff |
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Term
| Abortion in mares due to EVA are normally associated with what other disease presentation? |
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Definition
| -respiratory disease (40-50% of mares at risk will abort) |
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Term
| Why is EVA calles arteritis virus? |
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Definition
| -the virus replicates predominantly in macrophages and in the endothelial cells of blood vessels |
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Term
| What processes during EVA infection result in widespread hemorrhages and edema? |
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Definition
| -severe necrotizing panvasculitis and thrombosis of arterial wall (arteritis) |
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Term
| Why does abortion in EVA? |
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Definition
| -severe necrotizing myometritis |
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Term
| In the stallion, EVA establishes infection in the ampulla of 50% of infected recovered stallions, and the persistent infection is both ______ and ______. |
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Definition
-inapparent
-testosterone-dependent |
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Term
| What shows on an aborted fetus due to EVA infection? |
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Definition
| -severe necrotizing panvasculitits |
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Term
| True or False: EAV can be isolated on TC from blood and infected fetus. |
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Definition
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Term
| Our goal is to perform a FA test on fixed EVA-infected TC cells. What samples do we submit? |
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Definition
-nasopharyngeal and conjunctival swabs, and unclotted blood (citrate, EDTA)
-also placenta and lungs from aborted foals |
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Term
| RT-PCR is available for the detection of EAV in nucleic acid extracted from samples. For RT-PCR for EAV, what samples do we submit? |
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Definition
| -acute blood in EDTA and semen for stallions |
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Term
| True or False: Any stallion that is serologically positive could be secreting virus in its semen. |
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Definition
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Term
| What kind of vaccine do we have for EVA? |
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Definition
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Term
| True or False: Vaccianted stallions cannot carry the EVA virus. |
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Definition
| -FALSE, vaccinated stallions can still carry the virus |
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