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TV2001 > Parasitology - Lecture 5 > Flashcards

Parasitology - Lecture 5 Flashcards

1
Q

What are the general features of Order Ascaridida?

A
  • big (up to 50cm), white/ opaque, stout bodies
  • most have 3 lips around mouth
  • Posterior M is usually curved with 2 spicules
  • very prolific
  • eggs have thick shell (high survival rate),usually one cell inside
  • larvae reach L3 within egg
  • location: normally SI
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2
Q

What Ascarids infect pigs?

A

Ascaris suum

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3
Q

What Ascarids infect horses?

A

Parascaris equorum

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4
Q

What Ascarids infect cattle?

A

Toxocara (Neoscaris) vitulorum

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5
Q

What Ascarids infect dogs?

A

Toxocara canis

Toxascaris leonina

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6
Q

What Ascarids infect cats?

A

Toxocara cati

Toxascaris leonina

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7
Q

What are the general features of Ascaris suum?

A
  • dont seem to mature in ruminants, rabits,humans, etc. but will infect them
  • most common GIT worm in pigs
  • high prevalence in pigs younger than 6 months
  • physically identical to Ascaris lumbricoides (the humn ascarid)
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8
Q

Where does Ascaris suum locate in the host?

A
  • Adult: SI, but can be found in stomach, bile ducts and pancreatic ducts in heavy infections
  • Larvae: migrate to liver, heart lungs, coughed up, small intestine.
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9
Q

What is the significance of Ascaris suum to humans?

A

can infect and mature in humans, possibly cause VLM

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10
Q

What is the morphology of Ascaris suum?

A
  • size: up to 45cm,
  • body: stout, pinkish yellow
  • posterior (M): conical, bent, 2 equal spicules
  • F vulva is anterior to middle of body
  • eggs: brown-yellow. thick, mammilated shell. contains one cell
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11
Q

Describe the lifecycle of Ascaris suum?

A
  • 200,000 eggs/ day
  • eggs very resistant to stress
  • 30-33C to develop
  • L3 forms inside egg
  • L3 containing eggs ingested by host, hatch in intestine and burrow into wall
  • reach liver within 24 hrs. reach heart and lungs via blood
  • coughed up and swallowed and mature in intestines,
    PPT = 60 days
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12
Q

What species and where does Parascaris equorum infect?

A
  • adults: SI of horse

- Larvae: migrate through liver, heart, lungs and back to SI

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13
Q

Describe the morphology of Parascaris equorum

A
  • size: up to 50cm
  • body: whitish, stout worms
  • anterior: 3 lips around mouth, large anterior end
  • eggs: brownish, thick-rough shell, 1-2 cells inside
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14
Q

What is the lifecycle of Parascaris equorum?

A

same as Ascaris suum

PPT= 80 days

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15
Q

What species and where does Toxocara vitulorum locate?

A

adults in SI of calves

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16
Q

what is the morphology of Toxocara vitulorum?

A

size: 15-40cm
anterior: 3 lips, cervical alae present but reduced. \
eggs: thick shelled, finely pitted outer coat, 1 cell inside

17
Q

describe the lifecycle of Toxocara vitulorum

A
  • eggs passed in poop
  • host ingests embryonated eggs, but dont develop patent infection.
  • larvae hatch, migrate to liver, lungs, muscles, brain, etc and arrest
  • migrate to mammary glands during partuition and pass to calf.
  • develop in SI of calf with no migration
  • calves shed eggs in poop
18
Q

What is the human significance of Toxocara canis?

A

zoonotic potential. can cause VLM and OLM and other syndromes

19
Q

what is the morphology of Toxocara canis?

A

size: 10-18cm
anterior: 3 lips, cervical alae present and end gradually posteriorly
Posterior: til of M has caudal alae and terminal digitiform appendage. subequal spicules
eggs: subspherical, thick shelled, finely pitted outer coat, dark brown, contain 1 cell

20
Q

What is the lifecycle of Toxocara canis?

A
  • F are prolific
  • 25-30C best temp
  • L3 develop in egg
  • infect by ingestion of eggs, hatch in duodenum and undergo either tracheal or somatic migration (and arrest)
  • hypobiotic larvae are reactivated during pregnancy and infect puppies through milk or via placenta or infect SI of female.
  • may also arrest in paratenic hosts
21
Q

What factors affect whether a parasite undergoes somatic or tracheal migration?

A
  • age
  • immunity
  • sex
  • size of infective dose
22
Q

Where does Toxocara cati infect?

A

small intestine

23
Q

What is the significance of Toxocara cati on human health?

A

can infect humans and cause VLM and OLM

24
Q

what is the morphology of Toxocara cati?

A

size: 3-10cm
anterior: 3 lips, large cervical alae that end abruptly (looks like arrow)
eggs: dark brown, thick, pitted, 1 cell in egg

25
Q

What is the lifecycle of Toxocara cati?

A
  • eggs shed in poop and mature to L3 inside egg
  • L3 eggs ingested, larvae hatch and either tracheal or somatic migration
  • tracheal mature in SI
  • somatic not passed to kittens via placenta, but will via milk
  • probability of tracheal migration is high
  • can arrest in paratenic hosts
26
Q

What is the location in the host of Toxascaris leonina?

A

small intestine

27
Q

What is the morphology of Toxascaris leonina?

A

size: 5-10cm
anterior: 3 lips. long cervical alae
eggs: oval, thick shell, smooth outer layer, 1 cell inside

28
Q

What is the lifecycle of Toxascaris leonina?

A
  • fast embryonation of eggs
  • infect host by ingesting L3 eggs or paratenic hosts
  • no tracheal migration, mature in intestine.
    PPT = 2 months
  • no prenatal or milk transmission
29
Q

What ascarids infect birds?

A

Ascaridia galli
Heterakis gallinarum
Heterakis isolonche

30
Q

What species and where does Ascaridia galli infect?

A

SI of chicken, turkey, goose, etc.

31
Q

Describe the morphology of Ascaridia galli

A

size: 3-12cm
anterior: 3 large lips
posterior (M): caudal alae, 10 pairs of papillae, circular precloacal sucker with thick cuticular rim
posterior (F): straight, conical
eggs: elipsoidal, thick, smooth shell, 1 cell inside

32
Q

what is the lifecycle of Ascaridia galli?

A
  • birds shed eggs in poop
  • L3 develop in egg (5 days at best temp)
  • host ingests eggs with L3
  • mature in SI
    PPT 6-8 weeks
33
Q

What species and where does Heterakis gallinarum infect?

A

caecum of chickens, turkeys, geese, ducks, phesants, etc.

34
Q

what is the morphology of Heterakis gallinrum?

A

size: 7-15mm
anterior end: mouth with 3 lips, 2 alae, oesophagus ends in well developed bulb
posterior end (M): large caudal alae, circular precloacal sucker, unequal spicules
posterior end (F): long, narrow and pointed
eggs: similar to ascaridia galli. elliptical, lateral sides almost parallel, thick, smooth shelled, one cell inside

35
Q

What is the lifecycle of Heterakis gallinrum?

A
  • eggs shed in poop
  • ingestion of L3 embryonated eggs or ingestion of earthworms, grasshoppers, flies, etc with eggs
  • L3 hatch in SI, migrate to caeca and molt to adults in 4 weeks
36
Q

Describe the pathogenicity of Heterakis gallinrum. why is this significant?

A

considered non-pathogenic. important because it is a vector for Histomonas meleagridis

TV2001 (21 decks)

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