FA Q4, Parasites, I

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  1. what species of ruminants are more susceptible to parasitism?
    small ruminants
  2. what stage of nematode is infective?
    How are L3's destroyed naturally?
    • L3 (encased in cuticle)
    • dry out in sun light
  3. what stage of nematode is free living and microbivorous?
  4. what stages are major problem to the host?
    L4 and L5/adults when come out of hypobiosis -

  5. what are two common parasites that do not respond well to ivermectin?
    • Trichuris
    • Nematodirus
  6. what are two parasites that can lead to anemia as major cause of disease?

    Where do they reside in GI tract?
    • hemonchus contortus - abomasum
    • trichuris ovis - cecum
  7. what other abomasal parasite is important?
    ostertagia (circumcinta and trifurcata)
  8. What is barber pole worm?
    Is it a high or low shedder?
    What species is most affected?
    • hemonchus contortus
    • High shedder
    • sheep/goats (don't dev'l immunity with age like cattle)
  9. what are clinical signs of hemonchus?
    Is diarrhea expected?
    • *anemia*
    • hypoproteinemia - bottle jaw, ascites

    No- N feces, digestion NOT impaired
  10. where does hemonchus reside in the ruminant?
    Is there hypobiosis stage?
    • abomasum
    • yes, hypobiosis
  11. how is hemonchus diagnosed?
    • fecal float
    • see adults grossly at necropsy
  12. what is the brown stomach worm?
    Where does it reside?
    ostertagia lyrata

    • Abomasum
    • Parietal glands (can't secrete HCl)
  13. what is the difference between type 1 and 2 ostertagia lyrata?
    • 1: no hypbiosis/immediate molt to adult and lay eggs so see eggs on fecal count
    • 2: hypbiosis - signs show before mature/laying eggs - no eggs on fecal float
  14. why are pepsin levels increased in serum with ostertagia infection?
    • parietal glands destroyed= No HCl
    • Pepsinogen released
    • Abomasum:Pepsinogen⇏Pepsin (too alkaline)
  15. Is young animal on pasture for first time more likely to be affected by type 1 or 2 ostertagia?
    type 1 (classic form)
  16. C/S with light ostertagia worm burden?
    • 30% decrease in wt gain and milk production
    • 10% decrease in wool production
  17. what are expected signs with heavy ostertagia worm burden? 4
    • maldigestion
    • diarrhea/loose stool
    • emaciation
    • death
  18. what is seen at necropsy with ostertagia infection?
    moroccan leather abomasum (white nodules)
  19. what is bankrupt worm?
    Where does it reside?
    • trichostrongylus axei
    • abomasum and small intestine
  20. what are clinical signs associated with trichostrongylus? 5
    • Most asymptomatic
    • Immune compromised
    • Watery diarrhea (green/black)
    • ++Wt loss
    • Protein loss/bottle jaw
  21. how is trichostrongylus diagnosed?
    • fecal float
    • adults in abomasum at necropsy
  22. What is thread worm?
    Where does it reside?
    • strongyloides
    • small intestine
    • (has free living form outside body)
  23. what is "scald"?
    external (free living) form of strongyloides penetrates interdigital space

    • Resembles foot rot
    • Lameness

    Dx: Baermann technique for larvae; float for eggs
  24. What does internal form of strongyloides do?

    How severe is this disease?
    Infects calves: migrates through tissues ⇨colostrum/milk⇨calf

    -healthy will not show signs
  25. what is infective stage of nematodirus?
    Direct or indirect?
    Where does it reside?

    Direct life cycle

  26. Is nematodirus hardy or easily destroyed in environment?
    High or low egg shedder?
    eggs persist even winter freeze

    Low egg shedder (1 or 2 on a float is significant)
  27. C/S seen with nematodirus?
    • Acute diarrhea
    • Fatal in young/weak
    • no signs in healthy
  28. what is a whipworm seen in ruminants?
    Where does it live?
    What is prepatent period?
    trichuris ovis


    60 days (most other worms PPP = 21d)
  29. Are trichuris eggs hardy or easily destroyed in environment?

    Direct or indirect?

    What stage is ingested?
    hardy- survive winter freeze

    Direct life cycle

    ingest egg containing L1 - hatches only after ingested
  30. C/S seen with trichuris ovis infection?
    • Healthy:
    • No c/s

    • Young/weak:
    • Loose, hemorrhagic stool
    • Anemia
  31. what GI parasites are particularly problematic in camelids?
    • Nematodirus
    • Trichuris
    • (not effectively treated w/ivermectin)
  32. what are the 3 classes of drugs used in food animal to treat parasites?
    • Benzimidazoles
    • Cholinergic inhibitors
    • Macrocyclic lactones
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FA Q4, Parasites, I

FA Q4, Parasites, I
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