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Clinical Parasitology > Cestodes > Flashcards

Cestodes Flashcards

(42 cards)

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1
Q

Cestode morphology

A

Flat, solid-bodied and segmented, with a scolex, neck, and strobila; they lack a digestive tract

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2
Q

What type of life cycle do cestodes have?

A

Indirect life cycles with at least 1 intermediate host

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3
Q

Describe the sexuality of cestodes

A

Hermaphrodites - sexual +/- asexual reproduction (depends on the larval stage)

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4
Q

How do Cyclophyllideans differ from Pseudophyllideans?

A
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5
Q

What is a metacestode?

A

The larval stage of cestodes

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6
Q

Describe the differences between the various metacestode stages of cyclophyllideans

A
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7
Q

Within a hydatid cyst, what can you find many of?

A

Endogenous cysts

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8
Q

Describe Dipylidium caninum (cucumber seed tapeworm)

A
  • DH: canids, felids, humans - ZOONOTIC
  • Habitat: SI
  • Morph:
    • Adults - up to 50 cm long, armed scolex, 4 suckers, bilateral genital pores
    • Egg packets contain multiple eggs, each 45 um—> hexacanth embryo
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9
Q

Describe the Dipylidium life cycle

A
  • Gravid proglottids break off in SI, are passed in feces or actively crawl out
  • Proglottids rupture, release egg packets
  • Eggs ingested by IH
    • Larval fleas
    • Chewing louse of dogs
  • Eggs develop into infective cysticercoid
  • IH ingested by DH (dog, cat, human)
  • Scolex attaches to SI, grows
  • Self- or cross-fertilization occurs
  • PPP = 2-3 weeks
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10
Q

Describe the disease caused by Dipylidium caninum

A
  • Usually non-pathogenic
  • typically “scooting across the floor”
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11
Q

Describe Taeniid tapeworms

A
  • Large worms
  • are armed - rostellum with double row of small + large hooks
  • have proglottids longer than they are wide
  • have single genital pore per proglottids (irregularly alternating)
  • have characteristic taeniid-type egg
    • ​embyrophore is brown and radially striated
    • Hexacanth embryo with 6 hooklets
  • live in SI as adults
  • are more pathogenic as metacestode than as adults
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12
Q

Describe the general Taeniid life cycle

A
  • Adult tapeworms attached to SI
  • Gravid proglottids pass in feces or migrate out
    • rupture releases eggs
  • IH ingests egg —> oncosphere hatches, penetrates SI mucosa —>enters circulation
  • Metacestode develops in various organs/tissues
  • DH ingests IH
  • Scolex released, attaches to SI and grows
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13
Q

Describe Taeniid taeniaeformis

A
  • DH: cats, other felids
  • IH: Rats, mice, other small rodents —> liver
  • Morph:
    • Adults - 60 cm long, armed, 4 suckers
    • Strobilocercus
  • Disease: Heavy infection — obstruction reported
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14
Q

What are these?

A

T. Taenoiaformis eggs

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15
Q

What is this parasite?

A

T. Taeniaformis strobilicercus in liver

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16
Q

Describe Taeniid pisiformis (rabbit tapeworm)

A
  • DH: Dogs
  • IH: rabbits, hares, occasionally rodents - peritoneal cavities
  • Morph:
    • Adults: 200 cm long, armed, 4 suckers
    • Cysticercus = pea sized
  • Disease: Heavy infection - constipation, ill thrift, pot-belly
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17
Q

Describe Taenia ovis (mutton tapeworm)

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A
  • DH: Dogs
  • IH: Sheep, goats — skeletal and cardiac muscle
  • Morph:
    • Adults 100-200 cm, armed, 4 suckers
    • Taenid eggs
    • Cysticercus
  • Disease: Heavy infection - constipation, pot belly, diarrhea
18
Q

Taenia hydatigena (ruminant tapeworm)

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A
  • DH: Dogs
  • IH: sheep, goats, sometimes pigs - peritoneal cavity
  • Morph:
    • Adults 75-100 cm long, armed, 4 suckers
    • Taenid eggs
    • Cysticercus
  • Disease: Heavy infection - constipation, diarrhea, pot-belly
19
Q

Describe Taenia multiceps (sheep coenurus worm, gip)

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A
  • DH: dogs, foxes, coyotes
  • ​IH: sheep, goats - brain, spinal cord
  • Morph:
    • Adults 40-100 cm long, armed, 4 suckers
    • Coenurus
  • Disease: heavy infection - constipation, diarrhea, pot belly
20
Q

Taenia serialis (rabbit coenurus tapeworm)

Study These Flashcards
A
  • DH: Dogs, foxes, coyotes
  • IH: Rabbits - SC and IM connective tissues
  • Morph:
    • Coenurus - Scolices lined up in rows (‘serialis)
  • Disease: same as other Taenids
21
Q

Echinococcus granulosus

Study These Flashcards
A
  • Distribution: Northcentral, midwestern and southwestern US
  • DH: Dogs, carnivores
  • IH: cattle, sheep, sometimes horses, pigs, humans
    • ​liver, lung, brain
  • ​Morph:
    • Adults 4-7 mm long (very tiny), armed, 4 suckers, 3-4 proglottids
    • Unilocular hydatid cyst
22
Q

What are you looking at?

Study These Flashcards
A

Echinococcus granulosus (adult)

23
Q

WHAT ARE THOSE

Study These Flashcards
A

Echinococcus granulosus hydatid cysts in liver and lung

24
Q

What are these?

Study These Flashcards
A

Enterococcus granulosus protoscolex

Inverted (left)

Everted (right)

25
Describe Entercoccus multilocularis
* Distribution: northern US * DH: dogs, cats, foxes * IH: dogs, rodents, **humans — liver, lung** * Morph: * Adults: 1-5 mm, 2-6 proglottids * **Multilocular** **hydatid** **cysts**, size depends on locaiton * **Budding daughter cysts infiltrate tissue like malignant tumor** * **​**Disease**:** * **​**DH: usually harmless, _can harbor thousands of adults_ * IH: domestic animals typically asymptomatic, humans - organ dysfunction
26
WHAT ARE THOSE
(Enterococcus multilocularis) multilocular hydatid cyst
27
What are these lesions associated with?
Enterococcus multilocularis
28
Why should you treat both Taenia and Echinococcus from wild canids with caution?
Because these species have indistinguishable eggs and Echinococcus eggs have zoonotic potential
29
Describe Spirometra mansonoides (zipper tapeworm)
* DIstribution: Southern US, down into S. America * DH: Cats, dogs, **raccoons** * Habitat**:** SI * IH**: copepod (1st), frog/snake/rodent/fish (2nd)** * **​**Morph**:** * **​**Adults up to 1.5 m long, **bothria**​, **medial uterine pore** * **​**Eggs light brown, **operculated**
30
Describe the life cycle of Pseudophyllidean tapeworms
* Adults in SI produce **operculated eggs** —\> shed into feces * Upon contact with water —\> **coracidium** develops and emerges * **Copepod 1st IH** ​ingests coracidium -\> develops into **procercoid** in body cavity * Vertebrate **2nd IH (frog, rat, snake)** ingests copepod * procercoid migrates to muscle, CT —\> develops into **plerocercoid/sparganum —\>** encysts * DH ingests 2nd IH —\> plerocercoid attaches to SI and grows * PPP: 10-30 days
31
Describe the disease caused by Pseudophyllideans
* Adult stages usually **non-pathogenic** * may cause V/D, weight loss * Larval tapeworms: **Sparganosis** * **​​**Dogs, cats, humans (**zoonosis**) * Infected via ingestion of 1st or 2nd IH, or use of 2nd IH as poultice on wound * Signs depend on final location of migrating sparganum (e.g. lungs, CNS) * Proliferative form rarely reported
32
What parasite caused these lesions?
Spirometra mansonoides (Sparganosis); this was a pneumothorax
33
Describe Diphyllobothrium spp. (Broad fish tapeworm)
* Distribution: worldwide * DH: **humans (primary)**, cats, dogs, bears, fish-eating mammals * IH: copepod (1st), fish (2nd) * Habitat: SI * Morph: Long adults with medial uterine pore and bothria w/ operculated egg * Disease: * Vomiting, diarrhea, wt loss * **Zooanthroponosis:** abd discomfort, weakness, nausea; pernicious anemia (B12 deficiency)
34
How does the Diphyllobothrium lifecycle differ from that of Spirometra?
* The second IH = freshwater fish * in dogs: PPP = 3-4 weeks
35
How do you diagnose Taenia and Dipylidium?
* Proglottids: in the feces, bedding, and perianal area, longer than the are wide * +/- eggs in fecal float
36
How do you diagnose Echinococcus?
* Proglottids are too small to notice * Eggs seen in fecal float, can also use coproantigen ELISA
37
How do you diagnose Pseudophyllideans?
* Proglottids in the vomitus or feces; wider than they are long * Eggs found in fecal float, can also do fecal sedimentation
38
What is the only method of differentiating Taenid and Echinococcus eggs?
PCR
39
How do you diagnose cestodes grossly?
* You can break open proglottids and examine for eggs * you can ID adult worms using their scolices * if you necropsy the IH, you can ID the metacestodes
40
What are the treatments for Pseudophyllideans?
**Praziquantel** (extra-label)
41
What is the treatment for Cyclophyllideans?
* **Praziquantel** - **only product approved for Echinococcus spp.** * Epsiprantel * Fenbendazole - _Taenia spp. Only_
42
How do you prevent cestode infestation?
* Prevent predation and scavenging * do not feed raw/undercooked meat or fish * Flea control * For pets with at-risk lifestyle, regular fecal monitoring and anthelmintic tx is recommended * Pets in Echinococcus-endemic areas should receive monthly praziquantel

Clinical Parasitology (7 decks)

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