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Diseases Caused by Rickettsiae Flashcards

Learn the causative parasite and vectors, clinical signs, treatment, Post mortem findings, control and some ID (75 cards)

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1
Q

Common name for Bovine Anaplasmosis

A

Tick-borne gall-sickness

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2
Q

Parasite causing tick-borne gall-sickness (Bovine Anaplasmosis)

A

Anaplasma marginale

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3
Q

ID

A

Bloodsmear stained with Diff Quick:

Anaplasma marginale

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4
Q

Parasite causing Anaplasmosis in sheep and goats

A

Anaplasma ovis

  • much less severe than in cattle
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5
Q

Bovine Anaplasmosis (tick-borne gall-sickness) often overlaps with:

A

Areas of Bovine Babesiosis (B. bigemina / bovis)

  • African / Asiatic redwater
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6
Q

Tick vectors of A. marginale

A
  • R. decoloratus
  • R. microplus
  • R. evertsi evertsi
  • R. simus
  • R. bursa
  • Hyalomma spp.
  • I. ricinus
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7
Q

Mechanical transmission of A. marginale

A

Biting flies

  • Stable flies ( Stomoxys calcitrans )
  • Horse flies ( Tabanus spp. )
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8
Q

ID

A

Stomoxys calcitrans

(Stable fly)

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9
Q

ID

A

Tabanus spp.

(Horse fly)

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10
Q

Causes of iatrogenic transmission of A. marginale (Bovine Anaplasmosis / tick-borne gall-sickness)

A

Needles and instruments used; contaminated with fresh blood

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11
Q

T/F: Intra-uterine transmission of A. marginale (Bovine Anaplasmosis) can occur

A

True:

The calf will be a carrier of the parasite at birth.

In exceptional cases it may lead to abortion or mortality soon after birth

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12
Q

T/F: Anaplasmosis often show a strong seasonal incidence.

A

True:

Disease outbreaks occur more commonly during the warmer summer and autumn months which coincides with the increased abundance and activity of ticks and biting-flies

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13
Q

Incubation period of A. marginale

A

From 3 - 8 weeks

Average 4 - 6 weeks

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14
Q

T/F: Calves up to 9 months are less likely to develop severe clinical signs after being infected with A. marginale

A

True:

Calves up to 9 months have a non-specific, age related resistance to A. marginale and will therefore be less likely to develop severe clinical signs

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15
Q

T/F: Susceptibility to severe disease (Bovine Anaplasmosis) increases with age

A

True for cattle

There seems to be no age-related resistance in sheep and goats

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16
Q

General characteristics of Bovine Anaplasmosis

A
  • Variable fever
  • Progressive anaemia
  • Jaundice
  • Constipation
  • Drop in milk production (precedes above)
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17
Q

How long does the disease, Bovine Anaplasmosis, last?

A

Generally 2-4 weeks

(it may be longer)

Recovery is very slow: up to several months

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18
Q

Common post-mortem findings of a fatal Bovine Anaplasmosis case

A
  • Severe anaemia
  • Jaundice
  • Splenomegaly
  • Hepatomegaly
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19
Q

Describe the macroscopic appearance of the spleen found on PM of a fatal Bovine Anaplasmosis case

A
  • Splenomegaly
  • Meaty consistency
  • Inner part of the spleen is dark red
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20
Q

Describe the macroscopic appearance of the liver found on PM of a fatal Bovine Anaplasmosis case

A
  • Hepatomegaly
  • Cut-surface varies in colour: Orange-brown to mottled-yellow
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21
Q

Describe the macroscopic appearance of the gall bladder found on PM of a fatal Bovine Anaplasmosis case

A
  • Distended
  • Contains a sticky, thick, brown or yellowish-brown bile
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22
Q

Common GIT lesions found on PM of a fatal Bovine Anaplasmosis case

A
  • Severe gastro-intestinal stasis, esp. the fore stomachs and colon
    • Omasal content = dry and impacted
    • Colon = hard, dry and bile stained faecal balls
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23
Q

What would you expect the urine to look like on PM of a fatal Bovine Anaplasmosis case?

A

Urine will be yellow to dark brown due to the presence of bile pigment

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24
Q

How will you diagnoses Bovine Anaplasmosis?

A

Characteristic clinical signs (anaemia, jaundice, constipation)

Microscopic demonstration of parasites in RBC’s on a blood smear from live/dead animal

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25
**How will you treat Bovine Anaplasmosis?**
Tetracyclines Imidocarb dipropionate - same dosage as preventative treatment for Bovine Babesiosis
26
**When will you treat Bovine Anaplasmosis?**
As early in the course of infection: * Before development of high parasitaemia * Before onset of severe anaemia
27
**What will be the best therapeutic plan for cattle recovering from Bovine Anaplasmosis (A. marginale)?**
* Separate infected animals from the herd * Provide shelter * Provide easy access to palatable feed & water * Supportive therapy: * Mild laxatives * Rumen stimulants * Appetite stimulants * Liver support * Blood trandsfusion in severe cases
28
**T/F: Cattle that recovered from Bovine Anaplasmosis will only retain immunity for that season.**
False: Recovered animals develop a life-long immunity BUT remaine carriers of the organisms thus becoming reservoirs of infection
29
**T/F: Persistent carrier state of A. marginale (Bovine Anaplasmosis) is considered and advantage**
True: 1. It insures prolonged immunity in the animals 2. It is a constant source of infection for ticks which will enhacen exposure of calves up to 9 months of age (non-specific, age-related resistance)
30
**T/F: You can vaccinate calves against Bovine Anaplasmosis (A. marginale)**
True: You can vaccinate calves by effectively giving them a mild form of the disease during the period that they have a non-specific, age-related resistance (up to 9 months)
31
**What is the Anaplasmosis vaccine?**
Deep frozen blood from cattle infected with A. centrale (Closesly related to A. marginale but less likely to cause serious disease)
32
**T/F: Vaccinating with A. centrale prevents Bovine Anaplasmosis completely**
False: A single vaccination protects cattle against the severe clinical disease and death
33
**What are the best control measures in A. marginale (Bovine Anaplasma) endemic areas?**
Judicious tick control & Regular use of Anaplasmosis vaccine in calves
34
**Parastie causing Heartwater in cattle**
Ehrlichia ruminantium
35
**The main vector of E. ruminantium in SA**
Amblyomma hebraum ( South African bont tick)
36
**ID this vector of E. ruminantium (Heartwater)**
Amblyomma hebraum ( South African bont tick)
37
**Incubation period of Heartwater (E. ruminantium) in cattle vs sheep and goats**
Incubation period of Heartwater (E. ruminantium) Cattle: 14 - 18 days Sheep & Goats: 11- 13 days
38
**At what age do calves, lambs and kids have an age-related resistance to Heartwater (E. ruminantium)?**
Calves: \< 3 weeks Lambs & Kids: \< 1 week
39
**T/F: The age-related resistance calve, lambs and kids have against Heartwater (E. ruminantium) protects them completely from becoming infected**
False: It does not protect them from becoming infected, it protects them against the development of the clinical disease
40
**Common characteristics of Heartwater (E. ruminantium)**
* Fever of 40 degrees celcius that persists for 3 - 6 days * Severe, often bloody diarrhoea * Nervous signs
41
**List common nervous signs of cattle suffering from Heartwater (E. ruminantium)**
* Animals moves unsteadily in circles * High-stepping gait: more pronounced in front limbs * Collapse in convulsions * Lie on side with opisthotonus * Frequent bouts of leg-paddling or legs extended and stiff * Hypersensitivity to light and noise
42
**What is your most likely diagnosis?**
Heartwater (E. ruminantium) - Pedalling due to oedema on the brain
43
**How can you test for hypersensitivity in a suspect Heartwater (E. ruminantium) case?**
Slight tapping on the forehead will result in an exaggerated twitching of the eyelids
44
**What is the pathophysiology of Heartwater (E. ruminantium)**
E. ruminantium invades the endothelial cells (lining the blood vessels) = increased permeability Result = odoema & small haemorrhages into various tissues and body cavities
45
**Describe the most common PM findings of a fatal Heartwater (E. ruminantium) case**
Severe accumulation of fluid in the pericardium andmthorax and sometimes a small amount of fluid in the abdominal cavity
46
**Describe the physical characteristics of the fluid you would expect to find on a Heartwater (E. ruminantium) PM**
The fluid will be yellow ad clear (could also be cloudy) and may coaggulate on exposure to air
47
**ID: What is your most likely diagnosis?**
Hydrothorax with a yellow, clear fluid Heartwater (E. ruminantium)
48
**How will you diagnose Heartwater in a live animal?**
Characteristic clincial signs (Fever of 40\<, bloody diarrhoea, nervous signs)
49
**How will you diagnose Heartwater (E. ruminantium) in a dead animal?**
History - Characteristic clincial signs PM lesions (Hydropericarium, Hydrothorax, Brain oedema) Stained Brain smear (Diff Quick works) - Microscopic demonstration of parasites in the cells lining the small blood vessels
50
**ID**
Microscopic demonstrasion of E. ruminantium in a stained brain smear
51
**How will you treat Heartwater (E. ruminantium)?**
Short or long acting Tetracyclines \* Oxytetracycilne \* Doxycycline
52
**When will you treat for Heartwater (E. ruminantium)**
At the earliest possible stage
53
**T/F: Cattle recovering from Heartwater (E. ruminantium) develop immunity against the infecting parasite strain**
True: Cattle recovering from Heartwater (E. ruminantium) develop and immunity agains the infecting strain BUT remain susceptible to other strains of the parasite
54
**How will you protect new animals against Heartwater (E. ruminantium) when they are introduced to a Heartwater endemic area?**
Repeated routine Oxytetracycline injections: Administered over a sufficient period this will protect the cattle from contracting Heartwater while allowing them to develop a natural immunity
55
**T/F: You can vaccinate cattle against Heartwater**
True: A deep frozen vaccine containing sheep blood infected with virulent parasites (E. ruminantium) This will cause a predictable reaction allowing enough time to treat.
56
**The duration of immunity against Heartwater (E. ruminantium) depends on what?**
1. Host species 2. Infectin parasite strain(s) 3. Challenge parasite strain(s) 4. Whether cattle are regularly exposed to infected ticks (A. hebraum) to maintain immunity
57
**What is the best control measure for Heartwater (E. ruminantium)?**
Tick control: Efficient dipping or spraying Dip containig Cypermetrhin or Amitraz
58
**What is Q-fever?**
An acute febrile disease in humans
59
**Name the parasite that causes Q-fever.**
Coxiella burnettii
60
**What disease(s) does Coxiella burnettii cause in animals (production animals)?**
Coxiella burnettii does not usually cause disease in animals \* very rarely \* * Cattel: Late-term abortion * Sheep: Resorption / abortion (30%)
61
**T/F: Coxiella burnettii is ZOONOTIC**
True: It causes Q-fever in humans (acute febrile disease)
62
**How are domestic animals (cattle/sheep/goats) infected with Coxiella burnettii?**
1. When an infected tick feeds on them 2. Direct contact between infected animals
63
**How are humans infected with Coxiella burnettii (Q-fever)?**
1. When infected ticks feed on them 2. Drinking infected milk (not pasteurised) 3. Inhalation of aerosol/dust from infected foetal material, urine or carcasses
64
**What is the incubation period of Coxiella burnettii (Q-fever) in humans?**
Incubation period of Coxiella burnettii (Q-fever) is 14 - 26 days then a fever develops
65
**Common complaints of a person infected with Coxiella burnettii (Q-fever)**
1. High fever 2. Shivering and shaking 3. Joint pain 4. Headache 5. Poor response to ordinary pain-killers
66
**How do you diagnose Q-fever (Coxiella burnettii) in humans**
Antibody test
67
**T/F: Coxiella burnettii (Q-fever) is highly resistant to disinfectants**
True: Coxiella burnettii (Q-fever) will be destroyed by 30 minute exposure to 70% alcohol or 0.05% hypochloride
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Production Animal Diseases (2 decks)

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