LA Infectious Diseases- Hemolymphatics Flashcards
describe equine infectious anemia
- retrovirus with a simple RNA genome (8kb)
-gag, pol, env - infects macrophage/monocyte cell lines: causing systemic effects from cytokine secretion
- coggins test!!! REPORTABLE
-required for sale/movement in the US
-performed yearly by a USDA category II-accredited vet
-AGID: agar gel immunodiffusion = gold standard for testing, detects ANTIBODIES - prevalence is low in the US
describe infection/transmission of EIA
- infection via blood transfer:
-insect vectors: flies, mosquitoes
-iatrogenic: needles, surgical instruments, dental floats, bits, etc.
describe clinical signs and lab abnormalities of EIA, acute form
- sudden high fever (104-108)
- anorexia, depression
- weight loss
- petechiae (thrombocytopenia)
- jaundice (hemolytic anemia)
- ventral edema
lab abnormalities:
1. thrombocytopenia: earliest and most consistent abnormality
- anemia: intravascular and extravascular hemolysis, also affected erythropoiesis
- glomerulonephritis/vasculitis: antibody/antigen complexes
describe the disease course of EIA
- cyclical alterations in viremia, platelet counts, and temperature because if a lifelong disease with no cure
-acute/subacute: most common (thrombocytopenia precedes fevers)
-chronic: ill-thrift, acute/subacute attacks
-inapparent carrier: no clinical signs
describe how to manage EIA-positive horses
- causes lifelong infection!
- reactor and ALL horses within 200 yards are quarantined!!
- euthanasia or life-long quarantine for positive animals
describe bovine leukemia virus
- deltaretrovirus genus, retroviridae family
- lifelong infection, blood borne infection of lymphocytes
- 3 stages of disease
a. aleukemic: infected but cannot tell from outside, no changes, asymptomatic, no changes on initial bloodwork
b. a percentage of aleukemic animals go on to develop persistent lymphocytosis
c. a small percentage of persistent lymphocytosis animals will go on to develop lymphatic tumors
- 5% of cattle will develop signs
-mostly lymphosarcoma
-uterus, heart, abomasum, spinal canal, retrobulbar lymphatic tissue, sometimes LN enlargement
-10-20% persistent lymphocytes
describe the significance of BLV
- high prevalence in the US
-dairy: up to 90% of herds
-beef: up to 40% - carcasses of affected animals are condemned
- BLV is found in 1/2 of condemned carcasses in the US
describe testing for BLV
- if no clinical disease, test for antibodies
-AGID
-ELISA: higher sensitivity
-REPORTABLE!!!! - if clinical disease, can sample LN
describe BLV transmission
- blood/fluids with blood cells (lymphocytes)
-milk!!
-in utero: rare
-nasal secretions potentially
-insects that take a blood meal!! - iatrogenic spread
-DONT re-use needles!
describe babesia and theirelia in LA
- tick-transmitted hematic protozoa
- cattle: bovine sadness complex
-babesia bigemina, B. bovis
-theileria orientalis
-treatment: imidocarb, diminazene aceturate - equine piroplasmosis:
-babesia caballi
-theirelia equi
-treatment: imidocarb - REPORTABLE
describe anaplasma
- obligate intracellular bacteria
-coccoid to ellipsoidal - reside/replicate in vacuoles in cytoplasm of eukaryotic cells
- transmission:
-ixodid ticks
-eastern US: I. scapularis
-western US: I. pacificus, I. spinipalpis
describe anaplasma phagocytophilum, formerly erlichia equi (in horses)
- equine granulocytic anaplasmosis
- infects neutrophils and eosinophils
-forms mulberry-like colonies called morulae - causes fever, lethargy, inappetence, limb edema, icterus, ataxia, stiff gait
- clinical signs worse in adults than young horses (<1 year of age)
describe anaplasma marginale in cattle
- infects erythrocytes, causes extravascular hemolysis
- clinical signs:
-fever, pale MM, lethargy, icterus, gastrointestinal signs, weight loss, decreased milk production, abortion, death - younger animal = milder signs
describe testing and treatment for anaplasma
testing:
-blood smear: check for intracellular organisms
-antibodies
-PCR
-REPORTABLE diseases in LA
treatment:
-antibiotics: tetracyclines
-cattle vaccine available in some states
describe corynebacterium pseudotuberculosis
- gram positive, facultative intracellular coccobacillus
- goats and sheep: caseous lymphadenitis
- horses: pigeon fever
describe pathogenesis and clinical signs of caseous lymphadenitis due to corynebacterium pseudotuberculosis
- enters body via:
-wounds on skin (shearing, needles, puncture wounds, etc.)
-mucous membranes (resp or GI) - virulence factors:
-exotoxin: phospholipase D; damages endothelium, promoting hematogenous spread
-lipid coating: protects from digestion in the cell, promoting persistence of infection - clinical signs:
-abscesses: LNs, anywhere; internal in sheep, external in goats
-chronic weight loss (poor doers)
-lymphangitis
describe diagnosis of caseous lymphadenitis caused by corynebacterium pseudotuberculosis
- presumptive diagnosis:
-abscessed LNs
-serology: also used to screen herd - definitive diagnosis:
-bacterial culture of pus
(other abscess-causing bacteria: trueperella pyogenes, staph aureus, pasturella multicoda, and fusobacterium necrophorum)
describe treatment of caseous lymphadenitis caused by corynebacterium pseudotuberculosis
- cull and test the rest of the herd
- surgical: can and should if not cull; but only if you have a way to physically separate the animal from the rest of the herd or will likely contaminate everyone else!!!!!!
-lance or drain abscess, lavage
-resect LN - antimicrobials: tough
-long term penicillin + rifampin
–penicillin good for gram (-), rifampin enable entry to LN, but need to give IV because rumen so longterm admin is annoying for owners
-tulathromycin (systemic and intralesional)
- because recurrent rates are high, CL is not considered a curable disease
describe prevention of caseous lymphadenitis caused by corynebacterium pseudotuberculosis
- strict biosecurity and isolation measures
-ideally: cull affected animals
-if cannot cull, separate affected from unaffected - vaccinations available!
-must use on the species they are labeled for
-reduce disease prevalence but does not fully prevent disease
describe streptococcus equi ss. Equi/strangles
gram positive, beta hemolytic bacteria
virulence factors:
1. M protein: resists phagocytosis, is immunogenic
- polysaccharide capsule: enables attachment and resists phagocytosis
describe clinical presentation of strangles
VERY CONTAGIOUS!!!!
- fever
- nasal discharge: uni or bilateral
- regional lymphadenopathy
- parotid region swelling and/or pain
- stertor or stridor (breathing sounds)
- coughing
- dyspnea
- causes retropharyngeal LN abscesses
-seen on endoscopy, takes path of least resistance when rupture into guttural pouch leads to thick nasty nasal discharge when horse leans head down - metastatic/bastard strangles
-10-14d
-rule out for pigeon fever
describe strangles treatment and prevention
- lance and drain abscesses
- treat symptomatically: includes tracheostomy if needed
- antimicrobials:
-penicillin
-ceftiofur
-TMS/rifampin
