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What is a rickettsia?
- Specialized small gram-negative, rod to coccoid-shaped bacteria
- Ehrlichia, Anaplasma, Cowdria, Wolbachia, Neorickettsia
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Most rickettsial infections are treated with which class of antibiotic?
Tetracycline
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Many rickettsial organisms can be transmitted between cattle mechanically via human intervention. List five ways in which humans commonly act as mechanical vectors to transmit rickettsial organisms such as Anaplasma marginale.
- Dehorning
- Bleeding
- Castrating
- Ear tagging
- Vaccinating (fomites)
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The vector for Ehrlichia canis is _____?
Ticks
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What does Anaplasma platys cause?
Canine Infectious Cyclic Thrombocytopenia
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What is meant by the term "reservoir"?
Population of animals that carry the organism (example: raccoons are a reservoir for rabies)
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What are factors that increase an animals susceptibility to Mycoplasma haemofelis?
- Immunosuppressed
- FeLV positive
- Splenectomized animals
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How can Mycoplasma haemofelis be distinguished from stain precipitate?
Focus up and down. In focus with edge of RBC (on same focal plane as RBC). It's not refractile (shiny)
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Is Mycoplasma haemofelis detrimental to cats? Dogs? What does it cause?
It is detrimental to cats (1/3 of untreated cats will die and many of those that recover will have recurring episodes due to stress). Not detrimental to dogs. Causes Feline Infectious Anemia.
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What is the effect of EDTA on Mycoplasma haemofelis organisms and what should you do about it?
Will fall off of RBC. Make slide immediately.
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Can Mycoplasma haemofelis be ruled out by a negative blood smear? Why?
No, it can not rule it out because it could take awhile for it to show up on a smear. 50% false negatives
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What species is affected by Anaplasma marginale?
Cattle
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What does Anaplasma marginale cause?
Anaplasmosis
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Is Anaplasma marginale more severe in adults or young animals?
Adults
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What are the clinical signs of Anaplasma marginale?
- Depressions
- Inappetence (lack of appetite)
- Fever
- Decrease in milk production
- Weight loss
- Dehydration
- Icterus
- Death
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How is Anaplasma marginale spread?
- Ticks
- Biting flies
- Mechanical transfer (dehorning, bleeding, castrating, ear-tagging, vaccinating)
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How is Anaplasma marginale diagnosed?
- Small blue dots on edge of RBC up to 1 um diameter
- May not stain well
- Serological test available
- PCR
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How is Anaplasma marginale treated and controlled?
- Treated:
- Tetracyclines
- Limit stress
- Control vectors (insect and tick repellants)
- Fomites (don't mix with blood)
- Vaccine available
- Controlled:
- Doxycycline at least 1 month
- Tick control
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How is Eperythrozoon spread?
- Blood sucking insects (lice)
- Fomites (syringes and surgery)
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Who is affected by Eperythrozoon?
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What does Eperythrozoon look like?
- Coccoid, rod, and ring shaped
- On the surface of RBC
- In plasma
- Surrounding platelets
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Do Rickettsia have cell walls?
No. They can not survive outside a cell
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How are bacterial obligatory parasites (rickettsials and mycoplasma) spread?
Blood-sucking insects (ticks and fleas most common)
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What is a PCR test?
Tests for an organism's DNA
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What are the different organism in blood?
- Mycoplasma haemofelis
- Ehrlichia
- Anaplasma
- Eperythrozoon
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What is a fomite?
Inanimate object that transmit disease or parasite (hair brush, dehorners, surgical instruments)
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What is vector?
Living organism (usually an arthropod) that transmits disease (or transmit parasite)
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What are the two types of vectors?
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What is a biological vector?
Part of parasite's life cycle must occur within the vector (example: mosquito)
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What is a mechanical vector?
Parasite undergoes no life cycle change within the vector (the vector is only used to transport the organism)
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How is Mycoplasma haemofelis usually transmitted?
Fleas
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Mycoplasma haemofelis is seen in ____ of cats.
3-8%
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What does Mycoplasma haemofelis look like?
- Coccoid to rod-shaped
- Very small
- Stains blue
- On the edge of RBCs
- One to several per cell
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How is Mycoplasma haemofelis treated?
- Doxycycline
- Enrofloxacin (in Baytrl)
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When is Mycoplasma haemocanis seen?
only in splenectomized dogs
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Where are Ehrlichia canis seen on a blood smear?
Morula is in monocytes
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What happens as Ehrlichia canis affects marrow?
Pancytopenia (no RBC or WBC)
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How can Ehrlichia canis be transmitted?
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What are the clincial signs of Ehrlichica canis?
- Signs variable
- Fever
- Lymphadenopathy
- Splenomegaly
- Thrombocytopenia
- Inappetence
- Depression
- Fever
- Stiffness
- Edema of limbs
- Coughing
- Dyspnea
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How is Ehrlichia canis diagnosed?
- Blood work
- Serologic test available (Ab-may take weeks to develop)
- PCR
- May have mild normocytic, normochromic anemia, thrombocytopenia
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What type of cell does Anaplasma platys affect?
Platelets
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How is Anaplasma platys diagnosed?
- Serological tests
- Organisms are rarely seen on a blood smear
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When does thrombocytopenia occur with Anaplasma platys?
At 10-day intervals
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How is Anaplasma phagocytophilum diagnosed?
- 4DX test
- Mild to severe thrombocytopenia seen in more than 80% of acutely infected dogs
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What does Anaplasma phagocytophilum look like on a blood smear?
Membrane-bound vacuoles of intracytoplasmic organisms (morula) can sometimes be observed in circulating neutrophils
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What are the clincial signs of Eperythrozoon?
- Severity variable
- Most disease is mild and transient (only lasts a short time)
- Hemolytic anemia
- Fever
- Anorexia
- Icterus
- Weakness
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What parasite is on these cells?
Anaplasma Marginale (seen in cattle...on the margins of the RBCs)
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What is in this neutrophil?
Anaplasma Phagocytophilum (membrane-bound vacuoles of intracytoplasmic organisms (morula) seen on neutrophils)
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What is this arrow pointing to?
Anaplasma Platys (seen on platelets...causes canine infectious cyclic thrombocytopenia)
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What is on these platelets?
Anaplasma Platys
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What is on these platelets?
Anaplasma Platys
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What is on this monocyte?
Ehrlichia Canis
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What is on this monocyte?
Ehrlichia Canis
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What is on this monocyte?
Ehrlichia Canis
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What is on these RBCs?
Eperythrozoon (seen in swine, sheep, cows, and llamas...on RBC surface, in plasma, and surrounding platelets)
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What is on these RBCs?
Mycoplasma Haemofelis (coccoid to rod-shaped, stains blue, very small, on edge of RBCs, one to several per cell)
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What is on these RBCs?
Mycoplasma Haemofelis
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