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Microbiology > Exam #5: Cestode & Trematode Infection > Flashcards

Exam #5: Cestode & Trematode Infection Flashcards

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Biology 101 flashcards
1
Q

What are the characteristics of Cestodes?

A

Tapeworms

  • Segmented bodies
  • Hermaphoditic
  • Absorb nutrients (no gut)

*Largest of the intestinal parasites (20-40 feet)

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2
Q

What are the characteristics of Trematodes?

A

Flukes

  • Non-segmented
  • Hermaphroditic
  • Primitive gut
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3
Q

What are the three basic structures of adult tapeworms?

A

Scolex= rounded head of the worm, usually armed with hooks and suckers

Neck= area from which the new body segments are generated

Body (strobila)= a long segmented structure

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4
Q

What are individual segments of the strobila called? What is the importance of these structures?

A
  • Proglottids
  • Worms grow in length by generating new proglottids at the neck; thus, the most distal proglottids are the oldest
  • Oldest proglottids are self-contained hermaphroditic structures that produce eggs (gravid)
  • These gravid proglottids break off & are passed in feces
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5
Q

For which tapeworm infections are humans the definitive host?

A 
Taenia saginota (beef tapeworm) 
Taenia solium (pig tapeworm)*
Diphylobothrium lactum (fish tapeworm)
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6
Q

For which tapeworm infections are humans the intermediate host?

A 
Echinococcus granulosus (dog tapeworm) 
Taenia solium (pig tapeworm)*
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7
Q

What is Taenia saginota? Describe the lifecycle of Taenia saginota.

A

Beef Tapeworm

  • Cattle ingest eggs/ proglottids
  • Larvae invade the circulation
  • Encystation of larvae occurs in the muscle of the cow, called “cysticercus”
  • Humans ingest undercooked meat containing cysts & the digestive process causes the release of cysticerci
  • Scolex of the worm attaches to the intestines

*The worm will grow in the intestine until there is a mature adult tapeworm

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8
Q

What are the symptoms of Taenia saginota infection?

A

Generally asymptomatic

  • Mild abdominal pain
  • Feeling of fullness

*Note that infection can last YEARS and can grow up to 10-30 feet

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9
Q

How is Taenia saginota diagnosed?

A

Identification of proglottids or eggs passed by infected individual

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10
Q

What is Taenia solium? Describe the lifecycle of Taenia solium.

A

Pork tapeworm

  • Lifecycle is essentially identical to beef tapeworm lifecycle
  • Ingestion of encysted worm in pork muscle

*However, humans can become an intermediate host!

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11
Q

How do humans become an intermediate host of Taenia saginota?

A
  • Ingested eggs hatch in the intestine & release larvae known as oncospheres
  • Oncospheres burrow through the intestine & pass into circulation, where they encysts in the:
    Lungs
    Heart
    Brain
    Eye

Pathology develops because the parasite causes a space-filling lesion & because of the inflammatory response to the parasite.

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12
Q

Which is more common, beef or pork tapeworm?

A

Beef

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13
Q

What is the difference between intestinal & extraintestinal transmission of Taenia solium?

A

To get a pork tapeworm, you must EAT pork

To get systemic effects, must eat eggs of pork tapeworm, which can occur via human-human transmission

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14
Q

What is Cysticercus?

A

Extra-intestinal encystation of Taenia solium that creates a space filling lesion and induces localized inflammation

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15
Q

What is Neruocysticercosis?

A

A severe complication of extra-intestinal Taenia solium infection; encysts in brain

  • Seizure
  • Neurological defects
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16
Q

What is the presentation of Neurocysticercosis on MRI?

A

“Swiss cheese lesion”

17
Q

How is intestinal Taenia solium diagnosed?

A

Proglottids or eggs in stool

18
Q

How is extra-intestinal Taenia solium diagnosed?

A

Imaging

Serology

19
Q

What is Diphyllobothrium latum?

A

Fish tapeworm

*This is the largest tapeworm to infect man

20
Q

Describe the lifecycle of Diphyllobothrium latum.

A
  • Eggs passed into water
  • Egg hatches in water & is ingested by small fresh-water curstachains
  • Crustachian is ingested by fresh-water fish
  • Encystation of larvae occurs in the muscle of the fish
  • Undercooked, raw, or pickled freshwater fish is then consumed by humans
21
Q

What is the largest tapeworm infecting man?

A

Diphyllobothrium latum

22
Q

How is Diphyllobothrium latum transmitted?

A

Ingestion of raw or undercooked fish

23
Q

What are the symptoms of Diphyllobothrium latum infection?

A

Asymptomatic or mild

  • Transient nausea, abdominal pain, diarrhea
  • Infection with multiple worms can cause intestinal obstruction
  • Macrocytic anemia due to Vitamin B12 deficiency may be seen in elderly
24
Q

How is Diphyllobothrium latum diagnosed?

A

Eggs in stool

25
Q

What is Echinococcus granulosus? What is it similar to?

A
  • Dog tapeworm

- Similar to Taenia solium

26
Q

Describe the lifecycle of Echinococcus granulosus.

A
  • Dogs shed
  • Grazing animals ingest (sheep goat)
  • Dogs reingest (the dead intermediate animal)

Humans can come in contact with infected dog feces, leading to extra-intestinal encystation of oncospheres similar to the process that occurs with the pork tapeworm, Taenia solium

27
Q

What is hydatid cyst disease?

A
  • Infection in humans by Echinococcus granulosus oncospheres; these encyst & surround themselves in a hyaline membrane, which is called a “Hydatid cyst.”
  • Large fluid filled cysts containing 100-1,000 larvae
  • These lead to large space-filling lesions in humans, particularly in the liver
28
Q

What are the general features of trematodes?

A
  • Humans are the definitive host
  • Fresh water snails are intermediate host
  • Larval forms are released and acquired by ingestion
29
Q

What is Fasciolopsis buski?

A

Intestinal fluke

30
Q

Describe the lifecycle of Fasciolopsis buski.

A

asdf

  • Infects snails
  • Excreted from snails
  • Attached to water chestnuts
  • Ingested
31
Q

Where is Fasciolopsis buski found?

A

Throughout Asia and India

32
Q

What are the symptoms of Fasciolopsis buski infection?

A

Light= focal inflammation, intermittent diarrhea

Heavy= Continuous diarrhea, intestinal hemorrhage, ulceration, & abscess formation

33
Q

How is Fasciolopsis buski diagnosed?

A

Eggs in stool

34
Q

What are the liver flukes?

A

Fasciola hepatica

Clonorchis sinesis

35
Q

How is Fasciola hepatica infection acquired?

A

Ingestion of aquatic plants

36
Q

How is Clonorchis sinesis acquired?

A

Eating fish that are infected

37
Q

What are the symptoms of Fasciola hepatica infection?

A
  • Liver tenderness & hepatomegaly
  • Fever & eosinophila
  • Biliary obstruction may occur (jaundice
38
Q

How is Fasciola hepatica diagnosed?

A

Eggs in feces

39
Q

What is unique about heavy infection of Clonorchis sinesis?

A

Heavily infected individuals are 10-15x more likely to develop bile duct cancer

Microbiology (49 decks)

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