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Helminths Flashcards

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1
Q

What are helminths?

A

Worms! Invertebrates, Macroparasites

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2
Q

What Phylum do roundworms belong to?

A

Nematodes

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3
Q

What Phylum do Flatworms belong to?

A

Platyhelminthes

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4
Q

What phylum do thorny- headed worms come from?

A

Acanthocephala

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5
Q

Platyhelminthes can be divided into 2 classes. What are they and what is the common name of those within them?

A

Cestodes (tapeworms) and Trematodes (flukes)

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6
Q

Where can you find Nematodes?

A

Present in every imaginable habitat. Arctic, Soil, Deep Sea, ect

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7
Q

TRUE or FALSE: Nematodes are Coelomates?

A

No they are pseudoceolomates

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8
Q

What is the target of antihelmintic drugs?

A

Nerve function. It is necessary to survival for nematodes

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9
Q

What are key features of nematodes?

A
  • chitinous cuticle, presence of complete digestive system. - Sexual dimorphism, Reproduce sexually
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10
Q

Which nematode does not reproduce sexually?

A

Strongyloides

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11
Q

Male nematodes have what reproductive structure and what is it for?
BONUS: What is the structure made out of?

A

Males have copulatory bursa for grasping females, and copulatory spicules for guiding sperm.
Bonus: It is made out of a cuticle modification.

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12
Q

What are the 3 cuticular modifications in nematodes?

A
  • Various size/ shape of buccal cavity
  • leaf crown/ alae
  • Copulatory bursa
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13
Q

Which nematodes have a large Copulatory bursa?

A

Strongyles

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14
Q

What is the infective state of nematodes?

A

L3 and sometimes L1

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15
Q

What is the adult stage of nematodes referred to?

A

L5

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16
Q

Where are eggs shed from the nematode in regard to the host?

A

L1 in feces (sometimes in urine), some dont shed at all

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17
Q

What is the most common migration of nematodes?

A

Hepatic-Tracheal migration

(ascarids)

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18
Q

What kind of lifecycle do nematodes have?

A

Direct lifecycle, indirect lifecycle, oviparous, viviparous, ovoviviparous, obligatory,
facultative

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19
Q

Nematode development can be completed where?

A

Entirely at the predilection site.

Larvae/pre-adults can also migrate during development

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20
Q

Nematodes that generally develop ONLY in the gut are ?

A

Generally asymptomatic with low pathogenicity.

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21
Q

Where do larvae migrate to in the case of tracheal ascarid?

A

Larvae will migrate to the liver, lungs, and heart.

Can cause hepatic damage, respiratory signs, lung lesions, etc.

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22
Q

What are critical external components for larval/ egg development?

A

Temperature and Humidity

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23
Q

What is hypobiosis?

A

-Inhibited larval development to avoid adverse conditions for development and
maturation – adaptation to host and environmental conditions
- Development starts once condition become favorable

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24
Q

Give an example of parasites with thin egg shells?

A

Hookworm, Strongyloides

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25
Give an example of nematodes with thick egg shells?
Ascarids
26
What is periparturient?
When the immune system is compromised during parturition → increased number of eggs/larvae
27
What is spring rise?
Spring rise is the build of larvae of the egg during the spring
28
What stage of development is L5 in nematodes?
Adult
29
What are oncospheres?
A hatched hexacanth
30
Name the two morphological factors that help differentiate between Nematode eggs:
Egg shape Egg shell thickness
31
How do you diagnose infections of nematodes?
- Morphological identification - Identifying eggs/ larvae - Molecular/ serological testing.
32
Where can adult Nematodes be found?
In vomit and feces.
33
How can you ID Nematode eggs/larvae in feces ?
Eggs = fecal smear, flotation, sedimentation Larvae = Baermann method (larval sedimentation)
34
In case of Pig ascarid, larval migration from the intestine on to the liver and the lungs can cause what kind of damage to the pig?
hepatic damagerespiratory signs, lung lesions
35
What are the 6 major nematode orders?
1. ) Strongylida 2. ) Rhabditida 3. ) Ascaridida 4. ) Oxyurida 5. ) Spirurida 6. ) Adenophorea
36
What are some unique features of cestode anatomy?
* Flatworms - dorsoventrally flattened body. * Tiny (2 mm) to enormous (12 m) * Segmented body (Proglottids) 3 to 100s * Head with suckers (slit/cup like) - attachment or Bothria * Hemaphrodite * Acoelomate * Alimentary canal absent - feed by absorption * Body covered by tegument * Indirect life cycle
37
What is the segments of the cestodes body called?
Proglottids
38
The entire head of a Cestode is called a?
Scolex
39
What does the scolex give rise to?
The proglottids
40
How is being a hermaphrodite beneficial for Cestodes?
Cestodes can self fertilize and cross fertilize.
41
What does Acoelomate mean?
Lacking a coelum/body cavity.
42
What is the main function of the Cestodes Tegument?
The tegument's main function is nutrient absorption.
43
What kind of lifecycle do cestodes have?
Indirect. Most vertebrate intermediate hosts/ some arthropods.
44
Describe in detail the life cycle of the Cestode.
1. Larva develop into adults in the intestine of the definitive host 2. Egg with hexacanth larvae form in the definitive host 3. Contaminate feces (environment) 4. Egg with hexacanth larvae OR gravid proglottids (environment) 5. Ingested by intermediate host; eggs change into oncosphere; penetrate gut wall and reach various tissues. 6. Larvae (metacestodes) form cysts in various tissues (intermediate host) 7. Ingestion of intermediate host tissue with cysts containing infective larvae enter new definitive host 8. Cycle starts again
45
What are two important orders of cestodes?
Cyclophylidea Pseudophylidea
46
Within Cyclophylidea, what are the categories of tapeworms of veterinary importance?
Taeniid tapeworms: - Taenia spp. - Echinococcus spp. Non taeniid tapeworms: - Dipylidium - Mesocestoides - Moniezia - Anoplocephala
47
What is the main difference between Taeniid tapeworms and Non-taeniid tapeworms?
Egg morphology differs.
48
What are the two important genus's of pseudophylidea?
- Diphyllobothrium (fish tapeworm) - Spirometra (tapeworm of dog, cats and wild carnivores)
49
What are two important characteristics of cyclophylidea?
- Organ of attachment: Suckers - Eggs are non operculated
50
What are two important characteristics of pseudophylidea?
- Organ of attachment: Bothria - Eggs operculated
51
What kind of larvae do cestodes have?
hexacanth larvae
52
Define Hexacanth.
Hexacanth Canth = small hooks Hexa = 6 Usually can count 6 hooks in the egg.
53
What are cestodes infective larvae called?
Metacestode in final intermediate hosts.
54
What kind of cestode eggs are these?
All Taenia species have same egg morphology. The eggs have an embryo with 6 hooks (hexacanth larvae) and thick straited egg shell
55
What is contained within each proglottid?
A male and female reproductive system
56
What kind of cestode eggs are these?
Operculated eggs Diphyllobothrium and Echinococcus spp. ) have same egg Spirometra morphology – commonly called taeniid eggs. Moneizia (note, most trematodes have operculated eggs too)
57
What are tapeworms named according to?
Morphology of the cyst
58
What are the names of tapeworms cysts?
1. Cysticercus 2. Cysticercoid 3. Hydatid 4. Coenurus 5. Strobilocercus Cysticercus – A single protoscolex in a fluid filled cyst Hydatid cyst 6. Plerocercoid 7. Tetrathiridum
59
Cysticercus is a ?
Single protoscolex in a fluid filled cyst.
60
Metacestodes are named according to?
Morphology of cysts.
61
What is the adult morphology of trematodes ?
Flat, leaf like body Easily visible hermaphrodite Two suckers (Oral and ventral)
62
How many intermediate hosts do pseudophyllidean cestodes usually have?
2 intermediate
63
What kind of lifecycle do trematodes have?
Lifecycle is always indirect. Most have 2 hosts, some have 3 hosts (2 IHs)
64
What intermediate host must always be present in trematode lifecycles?
a snail ( terrestrial or aquatic)
65
What environmental factor is extremely important in the life cycle of most trematodes?
WATER
66
What is the name for the infective stage for most trematodes?
Metacercaria
67
Where do trematodes typically infect in the host?
Definitive host: may infect GI tract, Liver, Lungs, circulatory system
68
What kind of eggs do trematodes have?
Eggs are operculated except heterobilharzia)
69
What is a unique feature of fluke eggs is important to know?
It doesnt float. Sedimentation method is important
70
What is key morphology of acanthocephalans?
- No digestive tract, separate sexes, retractable spiny attachment (Proboscis)
71
What kind of lifecycle do acanthocephalans have?
indirect
72
what is the intermediate host for acanthocephalans
Arthropods (beetles)
73
TRUE OR FALSE:Ancanthocephalans are a very common group of parasites
False
74
In Acanthocephalans, how are nutrients absorbed?
No digestive tract. Nutrients absorbed through tegument.
75
Where are Acanthocephalans found?
Vertebrate digestive tracts
76
What is an important note for Acanthocephalan eggs?
- eggs are very heavy and contain larvae
77
What parasite is this?
Tapeworm
78
What is the image pointing at? Hint: This is a nematode
Spicule
79
What parasite is this cross section from?
Nematode or roundworms
80
What is this image of overall? What parasite is it from? and What are the red lines pointed at?
1. ) Buccal Cavity 2. ) Nematode 3. ) Teeth
81
What are the projections (indicated with the black arrow) in this photo?
Cervical Ale
82
What kind of parasite is this?
Trematodes
83
What kind of parasite is this?
Thorny headed worm or Acanthocephalans
84
The parasite that causes these lesions can travel a considerable distance before settling in their predilection site, what are they?
Larva Migrans
85
What is the opening indicated by the arrow called? What is it for? What phylum and order are they found in?
Bothria Function: Organ of attachment Phylum: Cestode Order: Pseudophylidea
86
Recap
87

Parasitology (10 decks)

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