Tick borne diseases Flashcards
What’s the causative agent of ehrlichiosis?
Ehrlichia canis
- gram (-)
- intracellular bacteria
How is Ehrlichiosis transmitted to dogs and cats?
arthropod or trematode vectors
What does Ehrlichia canis cause?
canine monocytic ehrlichiosis (CME)
- tick borne disease (Rhipicephalus sanguineus aka brown dog tick)
- infects circulating monocytes – forms morulae
What’s the pathogenesis of Ehrlichiosis?
Transmission: hours within attachments
Acute signs: 8-20 days post
What are the clinical signs of acute Ehrlichiosis?
- lethargy, inappetence, fever, weight loss
- organism replicates in the reticuloendothelial tissues –> lymphadenopathy, splenomegaly
- neurological signs
- thrombocytopenia
- transient proteinuria
What are some clinical signs of chronic Ehrliciosis?
can range from mild to life threatening
- bleeding tendencies
- ocular changes: anterior uveitis, retinal hemorrhage, retinal detachment, PU/PD, edema
- pancytopenia
- hypoalbuminemia, hyperalbuminemia, increase ALT, increased ALP
- immune complex glomerulonephritis, azotemia
How is Ehrlichiosis diagnosed?
- morulae within monocytes
- confirmed with serology (IFA, ELISA)
- takes 1-4 weeks for antibody detection post initial diagnosis
- paired testing may be needed
- positive serology doesn’t equate to active infection
- PCR alone is not enough for confirmation
How is Ehrlichiosis treated?
doxycycline
- intrinsic resistance to fluoroquinolone
What’s the causative agent of granulocytic ehrlichiosis?
Ehrlichia ewingii
How is E. ewingii transmitted?
by amyblyomma americanum ticks (lone star tick)
- white tail deer = reservoir
What are some clinical signs of E. ewingii infection?
- lethargy, anorexia, vomiting, diarrhea, neurological signs
- fever, neutrophilic polyarthritis
What’s the causative agent of anaplasmosis?
Anaplasma phagocytophilum
- causes granulocytic ehrlichiosis, just like E. ewingii
What’s the pathogenesis of anaplasmosis?
- transmitted via Ixodes spp
- morulae in neutrophils
- needs 24-48h attachment
- clinical signs in 1-2 weeks
What are the clinical signs of anaplasmosis?
- usually subclinical in dogs
- vague signs
- lethargy, fever, inappetance, scleral injection, unwillingness to move, lameness, stiffness
- thrombocytopenia
How is anaplasmosis diagnosed? how is it treated?
- serology: may be negative in acute illness, and seropositivity may indicate previous exposure (up to 8m prior)
- treatment = doxycycline
What does A. platys cause?
thrombocytic anaplasmosis
What causes salmon poisoning disease?
Neorickettsia helminthoeca
What’s the vector for salmon poisoning disease?
a fluke called Ananophyetus salmincola
How is salmon poisoning disease transmitted?
- the fluke infects snail –> cercariae leave the snail –> penetrates fish –> develops in kidneys, muscles, and other tissues –> ingested by dogs
What c/s signs does salmon poisoning cause in cats?
cats are not susceptible to salmon poisoning disease!
- but the fluke does develop in the in the intestinal tract
What are the c/s of salmon poisoning disease in dogs?
- the fluke matures in the intestines, then attaches to the GI tract –> N. helminthoeca infects and replicates within cells of the mononuclear-phagocyte system –> LNs, spleen, liver, lungs, and brain
- acute illness = anorexia, high fever
- later on: lethargy, weight loss, lymphadenopathy, v/d
- thrombocytopenia
- electrolyte changes, increased liver enzymes
How is salmon poisoning disease diagnosed? How is it treated?
- can see organism in LN!
- ova in feces
- PCR
- doxycycline
What’s the causative agent of Potomac horse fever?
Neorickettsia risticii
What’s the causative agent of rocky mountain spotted fever?
Rickettsia rickettsii
What’s the vector for rocky mountain spotted fever?
Dermacentor ticks (the American dog tick)
What’s the pathogenesis of rocky mountain spotted fever?
- need 4-24 hours for reactivation after tick attachment
- incubation period (median 7d)
- fever, lethargy, anorexia, and lymphadenopathy
- people: classic triad of fever, rash, and headache
- ocular signs
- neurological signs
- median time to death after onset of clinical signs = 8d
How is rocky mountain spotted fever diagnosed?
- antibody detection
- PCR
- titer needs convalescent phase to confirm, but it would take too long
- direct immunofluorescence or immmunoperoxidase on infected tissuesHo
How is rocky mountain spotted fever treated?
doxycycline
How do cats do with rickettsia disease?
rarely infected
- similar clinical signs as dogs
- treat with doxycycline
