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POD from G > 6.13 Spirurid Nematodes > Flashcards

6.13 Spirurid Nematodes Flashcards

1
Q

The Spiruridia order includes what worms

A

spirurids, filarids, guinea worm (Dracunulus)

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2
Q

what is the location of most Spiruridia

A

stomach worms, but also connective tissue and eyes

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3
Q

what is the stomach worm of dogs

A

Physaloptera

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4
Q

what is the stomach worm of dogs and cats

A

Spirocerca

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5
Q

what are the eye worms

A

Thelazia

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6
Q

what are the stomach worms of horses

A

Habronema/Draschia

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7
Q

All Spirurids have (direct/indirect) lifecycles and use ________________ hosts

A

indirect; arthropodan intermediate (also paratenic)

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8
Q

what are the migrations of Spirurids

A

simple (no tracheal or somatic and therefore no vertical transmission)

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9
Q

do Spirurids have a relatively long or short PPP

A

long

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10
Q

what are the intermediate hosts of horse stomach worms (Habronema/Draschia)

A

muscid flies: house flies and stable flies

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11
Q

describe the lifecycle of Habronema/Draschia

A

stable flies or house flies pick up larvae -> L3 or the flies are ingested by the horse -> mucosal migration in the gastric pits produces adults

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12
Q

what is the pathogenesis of Habronema and Draschia

A

Habronema invades the mucosa, causing chronic gastritis

Draschia invades the submucosa, forming tumor-like caseous nodules

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13
Q

T/F the gastritis and tumor-like nodules formed by Habronema and Draschia are responsible for the main disease

A

F; it is the larvae that cause the main burden of disease

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14
Q

Describe the pathogenesis and clinical signs of Habronema/Draschia megastoma

A

occurs in an immune host when flies lay larvae on the skin or conjunctiva that then attempt to migrate -> granulomatous inflammation activated by host -> inflammatory lesion produces sore -> weeping of sore attracts more flies -> propagation of the problem

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15
Q

can Draschia or Habronema be treated? with what?

A

Draschia cannot due to the tumor-like lesions

Habronema can be with moxidectin or ivermectin

Habronema and Draschia in the skin can be treated with ivermectin

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16
Q

what are the general features of all filarid nematodes

A
  • host-specific
  • require a blood-sucking insect as an intermediate host
  • generally infect CT or body cavities
  • long, slender adults
  • have microfilaria (pre-L1) stage
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17
Q

describe the pathogenesis and disease caused by Guinea Worm (Dracunulus)

A

adults live in the connective tissues of the legs -> creates hot blistering lesion -> when host puts their leg in water to relief the burning the female contracts uterus to release eggs -> intermediate host takes up eggs within the water -> intermediate host ingested

18
Q

what is the intermediate and definitive host of Acanthocheilonema reconditum

A

fleas; dogs

19
Q

where are adult Acanthocheilonema reconditum found

20
Q

what is the morphology of Acanthocheilonema reconditum
- adults
- microfilaria

A

adults are up to 5cm, slender

microfilaria parallel-sided anterior end

21
Q

describe the lifecycle of Acanthocheilonema reconditum

A

microfilaria in the blood of infected dogs -> fleas ingest microfilaria -> develop to L3 within the flea -> re-enters dog (grooming) -> adults in CT -> microfilaria produced by adults

22
Q

what is the pathogenesis and clinical signs of Acanthocheilonema reconditum

A

non-pathogenic and no clinical signs

23
Q

what are the IH and DH of Dirofilaria immitis

A

IH: mosquitos
DH: dogs, cats, ferrets, wild canids, seals, sea lions, humans

24
Q

what is the location of adult Dirofilaria immitis

A

right caudal lobar artery; other branches of pulmonary arteries; right ventricle in heavy infections

25
what is the morphology of adult and microfilaria Dirofilaria immitis
adults: slender, up to 35cm microfilaria: tapered anterior end
26
how can you tell apart male vs female Dirofilaria immitis
males have a curly tail
27
how can you distinguish Acanthocheilonema reconditum and Dirofilaria immitis
A. reconditum does not taper at the anterior end whereas D. immitis does; D. immitis makes more serpentine movements
28
what is the life cycle of Dirofilaria immitis
microfilaria in blood of host -> mosquito ingests microfilaria -> microfilaria develop to L3 in the mosquito under the correct conditions -> L3 move to the proboscis -> transmitted with next blood meal -> larvae move subcutaneously and lodge in the pulmonary circulation -> mature in the pulmonary arteries
29
what environmental conditions are needed for Dirofilaria immitis to develop in the mosquito
above 14 C for at least 7 days
30
when is heartworm transmission season in Canada
June - Oct
31
what is the pathogenesis of heartworm (assuming in a patient in an endemic area in the South)
arteritis in the pulmonary circulation; dead worms produce thromboemboli in the lung capillaries and arterioles -> inflammation Overall: increased vascular resistance and pulmonary hypertension Pulmonary hypertension produces right sided hypertrophy and CHF Congestion can produce liver damage
32
what is the presentation of heartworm in most dogs in Canada
asymptomatic
33
what are the ways to diagnose heartworm
- antigen test - Knotts test or Difil test for microfilaria
34
what is an important caveat to the test for heartworm: - antigen - microfilaria
antigen: most depend on antigen from reproductively active females (will not see if no females, senescent females, single worm infection, or prepatent period) microfilaria: some dogs amicrofilaremic but infected
35
what are the ways to treat Dirofilaria immitis
- adulticide (Immiticide) - surgery - microfilaricides (ivermectin, milbemycin) - prevention (ivermecin, milbemycin)
36
describe heartworm in cats
- very rare, more common in highly endemic regions - more extensive clinical signs with fewer worms (chronic tachypnea, coughing, abnormal lung sounds, vomiting) - usually amicrofilaremic
37
What is the benefit of antigen test for heartworm
* sensitivity of >90% * specificity of around 99%
38
What is the drawbacks of antigen test for heartworm
* predicative value relies heavily on prevalence * test must be run EXACTLY specified * no use in PPP * no use with senile worms * no use in single worm infection * no use in single sex infection
39
What are the benefits of microfilaria test (Knotts test or Difil)
* simple and relatively inexpansive * should differenciate between Dirofiliria immitis and Acanthocheilonema reconditum
40
What are the drawbacks of microfilaria test (Knotts test or Difil)
* only about 75% sensitive * some dogs are amicrofilaremic, but infected

POD from G (46 decks)

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