Rickettsia, Anaplasma, Ehrlichia, Neorickettsia

Question 1

What are the signs of Anaplasma phagocytophilum infection in dogs?

Answer 1

Fever, lethargy, anorexia, relucance to move, muscle pain

Lameness (similar in Lyme disease), polyarthritis, joint pain

Meningitis, pneumonia, GI signs

Question 2

What are the clinical signs of Neorickettsia risticii infection?

Answer 2

Anorexia, biphasic fever, mild depression, colic

May have: mild/moderate diarrhea, toxemia, dehydration, laminitis, edema

Question 3

During what stage of Anaplasma phagocytophilum do dogs show signs of disease?

Answer 3

During the acute bacteremic phase- not all animals will develop clinical signs though

Chronic or subclinical infections also possible

Question 4

True or false:

Anaplasma phagocytophilum infections have a high mortality rate.

Answer 4

False. It’s seldom fatal, however it can cause reduced weight gain and secondary infections.

Question 5

How is Anaplasma marginale treated?

Answer 5

Antibiotics- oxytetracycline

Will help infected animals survive acute infection but will not eliminate the carrier state

Question 6

How is Anaplasma phagocytophilum treated in cows and dogs?

Answer 6

Cows- short acting oxytetracyclines, sulfamethazine

Dogs- doxycycline

Question 7

What is the only intracellular organism known to infect platlets?

Which species are susceptible?

Answer 7

Anaplasma platys

Dogs, cats, humans

Question 8

How is Ehrlichia canis treated?

What is the prognosis?

Answer 8

Doxycycline

Prognosis good unless there is severe pancytopenia or aplastic bone marrow

Question 9

How is Neorickettsia risticii diagnosed?

Answer 9

PCR from blood or fecal samples, IFA

Question 10

How is Ehrlichia canis diagnosed?

Answer 10

Presumptive based on clinical signs and lab findings (thrombocytopenia, nonregenerative anemia, etc.)

Serology (SNAP, IFA), PCR

Question 11

Ehrlichia canis infects what cell types in the host?

Answer 11

Monocytes and lymphocytes

Question 12

What are the clinical signs seen in the acute phase of Ehrlichia canis infection?

Answer 12

Fever, lethargy, weight loss, anorexia

Thrombocytopenia with or without anemia, leukopenia

May have negative titer

Question 13

What are the clinical signs seen in the subclinical phase of Ehrlichia canis infection?

Answer 13

Few clinical signs

Mild thrombocytopenia, hyperglobulinemia

Positive titer

Question 14

Anaplasma phagocytophilum infects what cell types in the host?

Answer 14

Neutrophils and neutrophil precursors, endothlial cells

Question 15

How is Anaplasma phagocytophilum diagnosed?

Answer 15

CBC findings- severe transient neutropenia

Blood, buffy coat, or synovial fluid smears- can see morulae in neutrophils/eosinophils

Serology (SNAP test, IFA)

Question 16

What is the principle host species of Anaplamsa marginale?

Answer 16

Cattle

Question 17

What are the clinical signs of Anaplasma marginale infection?

Answer 17

Anemia (a PCV of less than 25%), blood is watery

Fever, anorexia, rumen stasis, rapid weight loss, weakness, staggering, pale MM, decreased milk production, abortion

Question 18

What are the clinical signs seen in the chronic phase of Ehrlichia canis infection?

Answer 18

Weakness, anorexia, weight loss, pallor

Lymphadenopathy, hepatomegaly, splenomegaly, nephropathies, retinal lesions, edema, nonseptic polyarthritis, CNS disease, death

Question 19

True or false:

If a SNAP 4DX test comes back positive for Ehrlichia, you can be positive the causative organism is Ehrlichia canis.

Answer 19

False. Both E. chaffeensis and E. ewingii can crossreact with E. canis on a SNAP test

Question 20

How is Anaplasma marginale diagnosed?

Answer 20

Blood smears, serology (SNAP test), PCR

Question 21

What are the clinical signs of Anaplasma phagocytophilum in ruminants and horses?

Answer 21

High fever (can be over 105ºF), coughing, decreased appetite, dullness, increased respiration and pulse

Can lead to hemorrhagic syndromes

Question 22

Neorickettsia risticii causes what disease in horses?

Answer 22

Equine monocytic ehrlichiosis

“Potomac horse fever”

Question 23

Anaplasma marginale infects what cell types in the host?

Answer 23

RBCs (form inclusion bodies), endothelial cells

Question 24

How are Neorickettsia risticii infections treated?

Answer 24

Oxytetracycline and supportive care