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Microbiology > Parasitology Exam 2: Cestodes > Flashcards

Parasitology Exam 2: Cestodes Flashcards

1
Q

What is another name for Cestodes?

A

Tapeworms

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2
Q

Scolex

A

head of cestode for attachment

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3
Q

Rostellum

A

crown of the scolex, may be smooth or have hooks

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4
Q

Proglottids

A

Segments that comprise the body of the tapeworm

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5
Q

Stobila

A

Body of the worm comprised of proglottids and scolex

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6
Q

Hermaphroditic

A

Organisms contain both male and female reproductive organs

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7
Q

Integument

A

Outer covering/skin of the organism that absorbs food

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8
Q

Oncosphere

A

Larva tapeworm within an embryonic envelope (infective stage)

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9
Q

Hexacanth embryo

A

6-hooked larva NOT enclosed in an embryonic envelope

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10
Q

List the names of intestinal cestodes:

A

D. latum (broad fish tapeworm)
D. caninum (cat/dog tapeworm)
H. nana (dwarf tapeworm)
H. diminuta (rat tapeworm)
T. solium (pork tapeworm)
T. saginata (beef tapeworm)

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11
Q

What is the largest human tapeworm?

A

D. latum

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12
Q

Tapeworms sexuality

A

Hermaphroditic

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13
Q

T/F: Cestodes generally require one or more intermediate hosts for the completion of their life cycle.

A

True

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14
Q

Specimen type for cestodes

A

Fresh or preserved stools for O&P

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15
Q

List a notable difference between cestodes and nematodes

A

Cestodes are hermaphroditic, while nematodes have separate sexes

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16
Q

What is another name for D. latum?

A

Broad fish tapeworm

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17
Q

Describe the life cycle of D. latum

A

AQUATIC LIFESTYLE
- Crustaceans (intermediate host) ingest coracidium larva which develops into procercoid larva.
- Fish (reservoir host) ingest the procercoid larva which develops into the plerocercoid larva.
- Humans (Definitive host) ingest fish infected with the plerocercoid larva which develop into adult worms in the small intestine.

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18
Q

Which is the only cestode to have an aquatic lifestyle?

A

D. latum

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19
Q

What disease does D. latum cause?

A

Diphyllobothriasis - may decrease host vitB12 levels –> pernicious anemia

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20
Q

Lab ID of D. latum

A

Visualization of eggs and/or proglottids in feces

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21
Q

Describe D. latum proglottids

A

Wider than long
Rosette-shaped central uterus

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22
Q

Describe D. latum scolex

A

Two shallow sucking grooves: bothria

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23
Q

Describe D. latum eggs

A

Operculated - lid at the end with knob at opposite end

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24
Q

Infective and diagnostic stage of D. latum

A

Diagnostic: eggs in feces
Infective: procercoid larva

25
Q

Which cestode has a cucumber seed appearance when they are wet, and grain of rice appearance when dry?

A

D. caninum (cat or dog tapeworm)

26
Q

D. caninum scolex

A

Rostellum - 4 to 7 rows of small hooklets

27
Q

Lab ID of D. caninum

A

proglottids or egg packets in the stool

28
Q

Infective and diagnostic form of D. caninum

A

Infective: cysticercoid larva
Diagnostic: prolottids/egg packets in feces

29
Q

How is D. caninum transmitted?

A

Accidental ingestion of fleas

30
Q

What is the most common tapeworm? Where is it most prevalent?

A

H. nana; Southern US

31
Q

What is different about H. nana from other tapeworms?

A

Intermediate host is NOT required, can be spread from person to person

32
Q

Infective and diagnostic stage of H. nana

A

Infective: ingestion of eggs
Diagnostic: eggs in feces

33
Q

Which cestode eggs are infectious and should be handled carefully?

A

H. nana, T. solium

34
Q

Describe H. nana eggs

A

4-8 polar filaments
Double membrane
Oncosphere has 6 hooks

35
Q

What population is most commonly infected with H. nana?

A

children

36
Q

How to differentiate H. nana from H. diminuta?

A

H. diminuta eggs lack polar filaments and are larger

37
Q

Diagnostic and infective stage of H. diminuta

A

Diagnostic: eggs in stool
Infective: Cysticerci in body cavity of insect ingested by rodent or human

38
Q

Life cycle of H. diminuta

A

Ingestion of arthropod infected with cysticercoids –> adult worms mature in intestine –> release of eggs
associated with rodents

39
Q

T. solium alternate name and transmission

A

pork tapeworm
Ingestion of raw or undercooked pork

40
Q

Which cestode is both a tissue and intestinal parasite?

A

T. solium

41
Q

T. solium/T. saginata infective and diagnostic stage

A

infective: cysticercus larvae in tissue
diagnostic: eggs or proglottids in stool

42
Q

T. solium disease

A

Taeniasis
Cysticercosis - organism forms cysts within host tissue outside of the intestine
Neurocysticercosis - organism forms cysts within tissues of the CNS

43
Q

T. solium and T. saginata eggs

A

striated shell
Cannot differentiate the two species’ eggs

44
Q

What is special about the therapy for T. solium?

A

Explusion of the scolex MUST be verified to assume satisfactory treatment

45
Q

T. saginata alternate name and transmission

A

Beef tapeworm
Ingestion of cysticerci in raw or undercooked beef

46
Q

Intermediate host and definitive host of T. solium and T. saginata

A

T. saginata intermediate host = cattle
T. solium intermediate host = pigs
both definitive hosts = humans

47
Q

T. saginata proglottids vs T. solium proglottids

A

T. saginata: 12-30 lateral uterine branches on each side

T. solium: 7-13 lateral uterine branches on each side

48
Q

T. saginata vs T. solium scolex

A

T. saginata does not contain hooklets, no rostellum

T. solium has 4 suckers with hooks in a double row

49
Q

Describe cestodes as a whole.

A

Long, segmented, ribbonlike body
Hermaphroditic - no separate sexes (asexual reproduction)

50
Q

What is different about tissue cestodes?

A

Tissue cestodes do NOT reach the adult stage in the human host (AKA humans are not the definitive hosts)

Organisms infect the human in their intermediate or cyst stage

51
Q

What are the two tissue cestodes discussed:

A

T. solium (pork tapeworm)
E. granulosus

52
Q

What disease does T. solium cause?

A

Cysticercosis
Most damage is caused by the severe inflammatory host response after the cysticerci have died

53
Q

Lab ID of tissue infected T. solium

A

ID of cysticerci in tissue

54
Q

Which is the smallest of all tapeworms?

A

E. granulosus

55
Q

What is the definitive host of E. granulosus? What is the intermediate/accidental host?

A

Definitive: dogs
Intermediate/accidental: humans
Humans are dead end hosts –> life cycle is unable to continue

56
Q

What cestode is associated with hydatid cysts? Where do these hydatid cysts mostly occur?

A

E. granulosus
Mostly occur in the liver causing cholangitis and cholestasis

57
Q

Infective and diagnostic stage of E. granulosus

A

Infective: ingestion of eggs/cysts
Diagnostic: ID of hydatid cysts in infected organ and positive serologic tests

58
Q

Which organism is this associated with: Ultrasound, MRI, and CT have improved the diagnosis and may provide visualization of the fluid-filled cysts. Calcified cysts may be visualized in x-rays.

A

E. granulosus

Microbiology (24 decks)

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