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Dealing with Threats > Parasitology - Nematodes > Flashcards

Parasitology - Nematodes Flashcards

1
Q

Name the 5 main routes of infection in which a helminth can enter and its life cycle can begin or continue?

A
  1. ingestion of infective stage
  2. ingestion of paratenic/intermediate host
  3. maternal
  4. skin penetration
  5. arthropod-borne
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2
Q

Are helminths macro or microparasites?

A

macroparasites

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3
Q

Helminths - complex or simple? multicellular or unicellular?

A

complex multicellular

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4
Q

What are the two reproductive products of helminths?

A

eggs (oviparous) or larvae (ovoviviparous)

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5
Q

Helminths are often _____ specific in its ______ host

A

host
definitive

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6
Q

What is the common transmission of helminths?

A

fecal-oral or maybe more appropriately environmental-oral

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7
Q

What are the two main subdivisions of Helminths?

A

Nematoda and Platyhelminthes

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8
Q

What are the two divisions of playhelminthes?

A

cestoda and trematoda

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9
Q

What is the morphology of nematoda?

A

thread, non-segmented, cylindrical, generally tapered at both ends

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10
Q

Which worm is considered to be “most successful”?

A

nematodes!

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11
Q

What is the general size of nematodes?

A

micrometers to meters

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12
Q

What do nematodes possess on their body surface? What does this allow for?

A

cuticle - restriction of growth

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13
Q

Explain the structure of the nematode’s cuticle

A

flexible similar to arthopod’s exoskeleton

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14
Q

Is the nematode’s cuticle metabolically active?

A

negative

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15
Q

What can a nematode’s cuticle form?

A

spines, ridges, secondary sexual structures

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16
Q

What is the nematode’s body cavity filled with? What is suspended in this cavity?

A

fluid
intestines and repro systems are suspended

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17
Q

What provides the nematode with movement?

A

body wall has a muscle layer

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18
Q

What neurotransmitters do nematodes possess?

A

acteylocholine and gaba

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19
Q

Explain the overall digestive system of a nematode

A

food depends on species and location in host
oral opening: buccal capsule
esophagus (pharynx)
intestine

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20
Q

Explain the overall repro system of nematodes

A

dimorphism
females usually larger and produce eggs or larvae
males have spicules for mating

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21
Q

Explain the overall development of nematodes

A

4 molts with each stage between molts referred to as L1, L2, L3, L4

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22
Q

Which nematode molt stage is typically considered to be infective?

A

L3 (L3 rule)

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23
Q

What shape are Strongylida?

A

round or circular

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24
Q

Why are Strongylida are considered bursate nematodes

A

bursa used in reproduction which holds female

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25
Q

Which order of nematodes is considered to be the most important species in the GI tract?

A

strongylida

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26
Q

Explain 4 pathogenic mechanisms of strongylida

A

damage from tissue
blood or tissue feeding
inflammation/immune response
anorexia

27
Q

What is the life cycle of strongylida?

A

direct

28
Q

What type of eggs do strongylida produce?

A

strongylid eggs

29
Q

Oval, thin shelled, morula containing eggs are called?

A

strongylid eggs

30
Q

What diagnostic technique is used when diagnosing strongylida?

A

fecal flotation

31
Q

Explain the general strongylid life cycle

A

-Eggs voided in feces
-L1 hatch and develop to L3 (with 2 molts)
-L3 retains cuticle of L2 as protective sheath
-L3 ingested by host in infective stage
-Larvae travel to predilection site and develop to adults

32
Q

What do L3 have to do to survive?

A

move into environment

33
Q

The cuticle retained in L3 from L2 is retained as protection but ______ eat. When metabolic reserves are exhausted they ____

A

cannot
die

34
Q

In general eggs and larvae dont like what 3 things?

A

temp extremes
freezing-thawing cycles
desiccation

35
Q

What are the 4 tropisms associated with Strongylida

A

Hydro +
Thermo +
Geo -
Photo +

36
Q

Where do strongylida spend a period of larval development before becoming adults?

A

gut wall before going into lumen as adult

37
Q

Explain what hypobiosis is in strongylida

A

Larva become dormant in host tissue site and wait for optimal condition to develop

38
Q

Which larval stages does hypobiosis occur in?

A

L3 or L4

39
Q

In hypobiosis, can parasites be detected?

A

nope

40
Q

What are 2 possible stimuli for arrested development?

A

environmental
host immunity

41
Q

What is the purpose of hypobiosis?

A

mechanism for optimizing chances of survival for next generation by synchronizing parasite life cycle with external events

42
Q

Explain immunity pertaining to strongylida

A

immunity develops gradually with active infection being required to be fully immunity stimulated

43
Q

What is premunition?

A

active infection being required to keep immunity fully stimulated

44
Q

What are 3 ways in which immunological compromise can shift balance in favor of a parasite and allow numbers to increase?

A
  1. parturition - periparturient egg rise
  2. malnutrition
  3. concurrent disease
45
Q

When does clinical disease develop?

A

when large numbers are present

46
Q

Which strongylida?most important ruminant helminths
slender
<10cm
GI parasites and one lungworm

A

trichostrongyloidea

47
Q

What is the life cycle of trichostrongyloidea?

A

typically strongyle

48
Q

What are the 3 trichostrongylye abomasal localized parasites?

A

haemonchus contortus/placei

ostertagia/teladorsagia

trichostrongylus axei

49
Q

What are the 3 trichostrongyle small/large intestine localized parasites?

A

trichostrongylus spp.
cooperia spp.
nematodirus spp

50
Q

The superfamily trichostrongyloidea have several genera that are in ruminant GI tract. All together what condition can they cause? What parasite is an exception to this?

A

parasite gastroenteritis

haemonchus

51
Q

What symptoms does PGE cause?

A

diarrhea
weight loss

52
Q

What do all grazing ruminants have in their GI tract?

A

a worm community

53
Q

What are the most important helminths in cattle?

A

ostertagia - brown stomach worms

54
Q

What is the most important helminths in small ruminants?

A

haemonchus contortus - barber’s pole worm

55
Q

Explain the life cycle of ostertagia

A

after ingestion (in abomasal) in L3 stage, larvae then enter gastric gland where they will molt to L4 - they are able to enter hypobiosis here and can remain for months until conditions are ideal. The larvae will then emerge into the abomasal lumen where it will molt to L5 and become an adult

56
Q

What is the most pathogenic change in the ostertagia life cycle?

A

L4 emerging into abomasal mucosa

57
Q

Explain the impact of larvae on gastric glands in ostertagia

A

nodules due to cell differentiation and hyperplasia with a reduction in acidity in abomasal fluid from a failure to activate pepsinogen to pepsin

58
Q

What is the clinical importance of ostertagia in adults vs young or immunocompromised animals?

A

adult and immune cattle have little/no effect - subclinical
young and immunocompromised animals get diarrhea, weight loss, hypoproteinemia - bottle jaw, death quickly

59
Q

What is haemonchus contortus?

A

abomasal parasite of small ruminants

60
Q

Why is haemonchus contortus more pathogenic than most of the other trichostrongyles?

A

blood feeding

61
Q

Which parasite have the adult stage as the most pathogenic - haemonchus or ostertagia?

A

haemonchus

62
Q

What is the clinical importance of haemonchus?

A

if amount of parasites is low, host can compensate blood loss and subclinical infection will occur but if there is a decreased host response or heavier infection with too much blood loss for the body to compensate for, it will result anemia, anorexia, bottle jaw - hypoproteinemia, weight loss, and death

63
Q

Explain the difference between type 1 disease vs type 2 disease and its relation to haemonchus and ostertagia

A

type 1
- caused by larvae that have developed without interruption
- represent accumulation of adult worms during grazing season
- usually occurs late-summer or autumn in pastured young animals

Type 2
- happens after larvae that have been arrested resume their life cycle
- synchronous emergence of arrested larvae
- occurs in late-winter or spring
- more common in ostertagia

64
Q

Any sheep or goat with anemia in the grazing season likely will be diagnosed with

A

haemonchus

Dealing with Threats (27 decks)

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