E2 Order Rickettsiales Flashcards

1
Q
Pathogen
Disease
Host
Mechanism
Immunity
Culture
Notes
A

???

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2
Q

What tissue are Rickettsiales (order) of bacteria tropic for?

A

Vascular endothelium or leukocytes

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3
Q

What is unique about Rickettsiales (order) bacteria transmission?

A

Arthropod vectors

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4
Q

What is the gram reaction & appearance of Rickettsiales (order) bacteria?

A

Gram-negative

Pleomorphic (variable shape)

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5
Q

What type of disease do Rickettsiales (order) bacteria cause?

A

Multisystemic disease

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6
Q

What is unique about the Rickettsiales (order) bacteria location in the animal?

A
Intracellular pathogen
(vascular endothelium or leukocytes)
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7
Q

Why is it difficult to culture or treat Rickettsia (genus) bacteria?

A

They are obligate intracellular pathogens

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8
Q

What cell types do Rickettsia (genus) bacteria target?

A

Reticuloendothelial system cells

endothelial cells & monocytes

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9
Q

What animals are incidental hosts of Rickettsia rickettsii? Why?

A

Humans & dogs

They do not have enough parasitemia to infect ticks (dogs may be able to cause infection in ticks)

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10
Q

What animals are normal hosts for Rickettsia rickettsii?

A

Small mammals

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11
Q

What is the arthropod vector for Rickettsia rickettsii?

A

Ticks

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12
Q

What disease does Rickettsia rickettsii cause?

A

Rocky mountain spotted fever (RMSF)

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13
Q

What is rocky mountain spotted fever (RMSF)?

A

Acute febrile infectious vasculitis

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14
Q

How long do ticks need to feed to transmit Rickettsia rickettsii?

A

6-24 hrs

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15
Q

What causes the spots in rocky mountain spotted fever?

A

Endothelial cell damage causes petechia

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16
Q

When do clinical signs appear from Rickettsia rickettsii in dogs?

A

2-14 days after infection

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17
Q

Do dogs require treatment for Rickettsia rickettsii infection?

A

Not usually

Most dogs eliminate the infection naturally

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18
Q

What can happen in dogs infected with Rickettsia rickettsii?

A

Vascular leakage
Edema
Hypotension
Shock

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19
Q

What is the best way to diagnose Rickettsia rickettsii infection in dogs (2 methods)?

A
  1. Visualization of the organism on blood smears
  2. Paired serum samples (antibodies)
    = single HIGH IgG titer
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20
Q

What is the most consistent lab finding in Rickettsia rickettsii infection?

A
  1. Thrombocytopenia

2. Fever 5 days after infection

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21
Q

How is Rickettsia rickettsii infection usually diagnosed?

A

Retrospectively

Dogs gets better with antibiotic treatment

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22
Q

Is there a vaccine against Rickettsia rickettsii infection?

A

No

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23
Q

Is there any evidence of Rickettsia rickettsii transmission from dogs to humans?

A

No

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24
Q

What is another family in the order Rickettsiales that is of veterinary importance?

A

Anaplasmataceae

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25
Q

What are some important genera in the family Anaplasmataceae?

A
  1. Anaplasma
  2. Ehrlichia
  3. Neorickettsia
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26
Q

What is the gram reaction, tropism and transmission of bacteria in the family Anaplasmataceae?

A
  1. Gram-negative
  2. Obligate parasites of erythrocytes (RBCs) & leukocytes
  3. Arthropod vectors = ticks & biting flies
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27
Q

What is the most pathogenic species of Anaplasma?

A

Anaplasma marginale

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28
Q

What does Anaplasma marginale infection look like microscopically?

A

Dense inclusion bodies in RBCs

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29
Q

Is Anaplasma marginale a reportable disease?

A

Yes!

30
Q

What animals can be infected with Anaplasma marginale?

A

Ruminants

Important disease of cattle in Gulf Coast region

31
Q

What age of cattle are most susceptible to Anaplasma marginale caused disease?

A
Adult animals 
(Host response = elimination of infected RBCs)
32
Q

What is special about Anaplasma marginale infection in calves?

A
  1. Are not usually clinically infected

2. Can become carriers

33
Q

How is Anaplasma marginale infection usually diagnosed?

A

Blood smears that show parasites

34
Q

Is there an effective vaccine for Anaplasma marginale?

A

No there have been attempts but no long term success

35
Q

What disease is caused by Anaplasma platys?

A

Infectious cyclic thrombocytopenia in dogs

Trophism for platelets!

36
Q

What is unique about infection with Anaplasma platys in dogs?

A

It reoccurs every 1-3 weeks = cyclic clinical signs

37
Q

How is Anaplasma platys infection usually diagnosed?

A
  1. Labs = thrombocytopenia

2. Antibody tests

38
Q

Is there a vaccine for against Anaplasma platys?

A

No

39
Q

What animal is the reservoir host for Anaplasma phagocytophilum?

A

Rodents

40
Q

What animals are affected by Anaplasma phagocytophilum as accidental hosts?

A

Horses,
Ruminants: elk, deer, cattle
Dogs
Humans

41
Q

What is the cellular tropism for Anaplasma phagocytophilum?

A

Granulocytes = Neutrophils

42
Q

Is Anaplasma phagocytophilum common in Minnesota?

A

Yes!

High seropositivity in dogs

43
Q

How is Anaplasma phagocytophilum usually diagnosed?

A
  1. Blood smears = morula in granulocytes

2. SNAP tests to detect Ag

44
Q

What are granulocytes (4 cells)?

A
  1. Neutrophils
  2. Eosinophils
  3. Basophils
  4. Mast cells
45
Q

Is there a vaccine for Anaplasma phagocytophilum?

A

No

46
Q

What three species of Anaplasma are important veterinary pathogens?

A

A. marginale
A. platys
A. phagocytophilum

47
Q

What is another genus in the family Anaplasmataceae that is of veterinary importance?

A

Ehrlichia

48
Q

What is the tropism, vector and clinical signs of Ehrlichia (genus) infection?

A

Intracellular parasite of WBC
Unknown vector transmission
Disease = leukopenia & anemia

49
Q

How does Ehrlichia (genus) survive in WBC?

A

Inhibits phagolysosome fusion

50
Q

What are two important veterinary species in Ehrlichia?

A

Ehrlichia canis & Ehrlichia ewingii

51
Q

What cells does Ehrlichia canis infect?

A

Monocytes

52
Q

What cell does Ehrlichia ewingii infection?

A

Neutrophils

53
Q

What the some clinical signs of Ehrlichia infection?

A
  1. Fever
  2. Hemorrhages
    = Epistaxis (nosebleed)
  3. Pitting edema
54
Q

Is Ehrlichia zoonotic?

A

Yes!

ALL species

55
Q

Why does Ehrlichia canis cause hemorrhages?

A

Infected monocytes adhere to vascular endothelium which cases leakage

56
Q

How is Ehrlichia canis diagnosed?

A
  1. Blood smear

2. Labs = nonregenerative anemia, hypoproteinemia, hypoalbuminemia, inc. liver enzymes

57
Q

Is there a vaccine for Ehrlichia canis?

A

No

58
Q

What is a third genera in the family Anaplasmataceae of veterinary importance?

A

Neorickettsia

59
Q

What disease is caused by Neorickettsia helminthoeca?

A

Salmon Poisoning Disease

Northwest US

60
Q

How is Neorickettsia helminthoeca transmitted?

A

Ingestion of FISH contaminated with FLUKES infected with N. helminthoeca

61
Q

What cells Neorickettsia helminthoeca infect?

A

Macrophages

62
Q

How severe is the disease caused by Neorickettsia helminthoeca?

A

Very severe

fatal if untreated

63
Q

How is infection with Neorickettsia helminthoeca diagnosed?

A
  1. Fluke ova in feces

2. Parasite in macrophages

64
Q

What disease does Neorickettsia risticii cause?

A

Potomac Horse Fever

equine monocytic ehrlichiosis

65
Q

How do horses typically become infected with Neorickettsia risticii?

A

Ingestion of fluke infected flies

Caddis flies

66
Q

What season it is most common to find Neorickettsia risticii infections?

A

Summer

Fluke’s host is a freshwater snail

67
Q

What are some clinical signs in horses with Neorickettsia risticii?

A
  1. High cyclic fever
  2. Explosive diarrhea = green/yellow
  3. May cause middle trimester abortions
68
Q

What is the best method to detect Neorickettsia risticii bacteria in a horse?

A

PCR

only bacteria species in this category

69
Q

Is there a vaccine against Neorickettsia risticii?

A

Yes!

but not guaranteed to prevent infection

70
Q

What is the emerging role of Wolbachia species in veterinary medicine?

A

Symbiosis with heartworm parasite

= eliminating the bacteria may kill the parasite