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Medical Microbiology > L24 (Worm Parasites) - B > Flashcards

L24 (Worm Parasites) - B Flashcards

1
Q

Four features of Cestodes (Tapeworms)???

A
  1. Monoecious (unisex)
  2. No digestive system
  3. Transmission by ingestion of ova
  4. Cause little or no harm – unless present in large numbers
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2
Q

What are three examples of tapeworms?

A

T. saginata
T. solium
D. latum

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3
Q

Which organism has the following features?
- Diecious
- Complete digestive system
- Wide variation in mode of transmission

A. Nematodes (Roundworms)
B. Cestodes (Tapeworms)

A

A. Nematodes (Roundworms)

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4
Q

Which three nematodes (roundworms) directly penetrate the skin with their infectious larvae?

A
  1. S. stercoralis
  2. N. americanus
  3. A. duodenale
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5
Q

Which three nematodes (roundworms) ingest contaminated soil?

A
  1. E. vermicularis
  2. T. trichiuria
  3. A. lumbricoides
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6
Q

Match the Cestode term to the definition…

____: Structure on anterior end of worm with suckers (+/- hooks) that functions to attach the worm to the intestinal cell wall

_____: Body of tapeworm; composed of many segments called proglottids

_____: Segments, each of which contains a complete set of sex organs (both M/F); can break off and pass out of body into stool

A. Scolex
B. Strobila
C. Proglottids

A

A. Scolex: Hooks on anterior end
B. Strobila: Tapeworm body
C. Proglottids: Segments that contain sex organs

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7
Q

_____: Mature, egg filled proglottids, located at posterior end of organism

____: Cysts formed by larvae embedded in body tissues

A. Cysticerci
B. Gravid Proglottids

A

B. Gravid Proglottids: Mature, egg filled proglottids, located at posterior end of organism

A. Cysticerci: Cysts formed by larvae embedded in body tissues

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8
Q

Which part of Cestodes are important for attachment? reproduction?

A

Attachment - Scolex
Reproduction - Proglottids

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9
Q

What three features of Cestodes can you used to differentiate them?

A
  1. Eggs
  2. Scolex
  3. Proglottids
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10
Q

True or False: The eggs of e. saginata and T. solium are indistinguishable from one another

A

True
- Both have radial striations on shell

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11
Q

Which of the following has four suckers and NO hooks?
A. T. solium scolex
B. T. saginata scolex

A

B. T. saginata scolex

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12
Q

Which of the following has four suckers and is “armed” with hooks (rostellum)?
A. T. solium scolex
B. T. saginata scolex

A

A. T. solium scolex

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13
Q

How do the gravid proglottids of T. saginata compare to those of T. solium?

A

T. saginata
- 12 to 20 uterine branches

T. solium
- 5 to 10 uterine branches

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14
Q

Describe the D. latum ova and gravid proglottid:

A

Ova
- operculum
- polar knob on opposite ends of egg

Gravid Proglottid
- rosette shaped uterine branches

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15
Q

Which of the following scolex has two grooved suckers, one on each side of the scolex?
A. T. saginata
B. T. solium
C. D. latum

A

C. D. latum

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16
Q

____ is the definitive host of T. saginata while ____ is the intermediate host of T. saginata

A

Human = definitive host
Cow = intermediate host

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17
Q

In T. saginata, cow will ingest embryonated eggs. Larvae migrate to tissues to become ____

A

cysticerci

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18
Q

How can humans become infected with T. saginata?

A

Ingestion of raw or undercooked beef

  • Upon consumption, stomach acids release of cysticerci from muscle tissue
  • Scolex attaches to intestinal wall + growth
  • Proglottids passed in feces
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19
Q

Life cycle of T. solium is similar to T. saginata, except in the case of T. solium ___ (intermediate host) eats embryonated eggs

A

Pig - intermediate host
Human - definitive host

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20
Q

What structure can you identify in feces to diagnose T. solium or T. saginata?

A

Proglottids

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21
Q

In D. latum, larvae hatch in the water and ___ eats them. Following this, minnow eat infected ____. Larger fish eats infected minnow.

A

copepod (small crustacean)

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22
Q

True or False: Pleurocercoid larva are ingested with infected raw fish in D. lactum

A

True

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23
Q

When D. latum infection occurs, scolex of____ attaches to mucosa.

Where does gravid proglottid break up?

A

pleurocercoid
colon

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24
Q

True or False: With D. latum infection, usually you will see eggs in feces (not intact proglottid)

A

True

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25
Q

Where are D. latum eggs deposited (where they will eventually hatch)?

A

Water

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26
Q

Definitive vs. Intermediate host of D. latum?

A

Human - definitive host
Fish - intermediate host

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27
Q

True or False: In D. latum infection, pleurocercoid larva is ingested with infected raw fish

A

True

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28
Q

Cysticercosis is an invasive human disease in humans, which can produce cysticerci in brain, eye, and muscles.

One can only develop this infection, however, if they ingest embryonated ____ eggs – in this case: human is intermediate (dead end) host
A. T. solium
B. D. latum
C. T. saginata

A

A. T. solium

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29
Q

Compare and contrast disease manifestation (Cysticercosis vs. Taeniasis) in T. solium:

A
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30
Q

What are the main signs and symptoms associated with Cestodes (tapeworms)?

A
  • Usually no symptoms!

1) Cysticercosis
- Occulocysticercosis: blindness
- Neurocysticercosis: seizures

2) D. latum can cause pernicious-like anemia

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31
Q

What are two ways to diagnose Cestodes (tapeworms)?

A

1) Mature worms in intestine
2) Proglottid or ova (D. latum) in fecal sample

32
Q

How do you r/o Cysticercosis?

A

1) CT/MRI - calcified lesions in brain, SC, or skeletal m
2) Serological (EIA) to worm antigens

33
Q

How do you prevent Cysticercosis?

A

1) Proper disposal of human feces
2) Routine meat inspection
3) Good personal hygiene

34
Q

What type of infections can be caused by Enterobius vermicularis (pinworm)?
A. Non-diarrheal, invasive
B. Non-diarrheal, non-invasive
C. Diarrheal, invasive
D. Diarrheal, non-invasive

A

B. Non-diarrheal, non-invasive

  • Note: most common intestinal nematode in the US
35
Q

True or False: Enterbiasis is a dioecious nematode (roundworm)

A

True

36
Q

Compare and contrast adult male vs. adult female Enterbius vermicularis adult worms:

A

Enterobius vermicularis

Adult male
- Curved, relatively blunt posterior end

Adult female
- Long, pointed tail

37
Q

Which parasite is inhaled/enters body via finger to mouth, leading to egg ingestion and larvae hatching in the small intestine, eventually migrating to the colon?

A

Pinworm (enterobiasis)

38
Q

True or False: Adult female pinworms migrate at night to perineum and lay eggs around anus, creating itching sensation

A

True

39
Q

What is the difference between autoinfection and retroinfection, as in the case of Enterobiasis (pinworms)?

A

Retroinfection: migration of newly hatched larvae from anal skin back into the rectum

Autoinfection: common form of transmission, by which infection occurs via egg ingestion due to contaminated hands, foods, toys

40
Q

How is enterobiasis transmitted?

A

Fecal oral route

41
Q

True or False: One can dx enterobiasis by looking at child’s stool or urine sample

A

False - you can rarely see pinworm eggs via stool or urine samples

42
Q

Which type of infections can arise due to T. trichiuria (whipworm)?

A

Non-diarrheal minimally invasive parasitic infestations

43
Q
A
44
Q

True or False: Whipworm larvae hatch in small intestine, then migrate to the colon. Mature in colon. Unembryonated eggs pass in feces, while those that are embryonate enter into the soil.

A

True

45
Q

Ingestion of embryonated eggs from soli leads to infection of ____

A

Trichuriasis

46
Q

What are the four soil-transmitted helminths?

A

1- Trichursis
2 - Ascaris
3 - Hookworm
4 - Strongyloides

47
Q

Prolapse rectum and dysentery are a side of infection by which parasite?

A

Trichuriasis (whipworm)

48
Q

How do you dx Trichuriasis?

A

Find ova in stool

49
Q

Three features of Trichuriasis?
- shape?
- color?
- stain?

A
  • Barrel shaped
  • Yellow-Brown
  • Bipolar unstained prominences
50
Q

How do you avoid getting sick with Trichuriasis?

A

Wash, peel, or cook raw veggies from the soil

51
Q

Which four parasites can cause non-diarrheal, invasive, parasitic infections?

A
  1. A. lumbricoides (giant worm)
  2. A. duodenale (hook)
  3. N. americanus (hook)
  4. Strongyloides stercoralis (thread)
52
Q

You are looking at an ova that has been identified as belonging to A. lumbricoides (giant worm). It is thick, transparent, and coarsely mammillated shell, typically golden-brown in color. Is it?
A. Fertilized
B. Unfertilized

A

A. Fertilized

53
Q

Describe lifecycle of A. lumbricoides:

A
54
Q

Describe lifecycle of A. lumbricoides:

A
55
Q

Signs and symptoms of A. lumbricoides?

A

1) Cough, sputum w/larvae + eosinophils
2) Pneumonitis

56
Q

Dx Ascariasis?

A

See ova microscopically in feces – prevent same way as Trichuriasis

57
Q

Necator americanus and Ancylostoma duodenale are ____, species that are intestinal parasites in human

A

hookworms

58
Q

What are the 3 stages of hookworm larvae?

A

1 - Embryonated
2 - Rhabditiform larva
3 - Filariform larva*

59
Q

True or False: The filariform larva stage is the infectious stage of hookworm

A

True

60
Q

True or False: On contact with human host, larvae of Hook worm penetrate skin and are carried through b. vessels to heart, then lungs

A

True

61
Q

How do hookworms cause blood loss in their host?

A

As adults, hookworms live in lumen of small intestine, where they attach to intestinal wall, results in blood loss for host

62
Q

Hook worm lifecycle?

A
63
Q

True or False: Hookworms can be acquired by walking barefoot

A

True

64
Q

Dx hookworms?
Sx of hookworms?
Prevention?

A

Thin-shelled eggs
Sx: anemia + protein deficiency
Prevention: wear shoes

65
Q

Humans are accidental hosts of zoonotic hookworms, can develop ___ ___ ___ (CLM)

A

cutaneous larva migrans

66
Q

True or False: Strongyloides stercoralis has a similar morphology to hookworm, but it less prevalent

A

True

67
Q

What is the infectious, third stage larvae of S. stercoralis larvae?

A

Filariform larvae

68
Q

Which larvae is used for diagnosis (diagnostic stage) of S. stercoralis?
A. Filariform larvae
B. Rhabditiform larvae

A

B. Rhabditiform larvae

69
Q

Which parasite is the only one that is known to have a free-living cycle that takes place in the soil?

A

Strongyloides

70
Q

Strongyloides life cycle?

A
71
Q

True or False: Strongyloides can do internal (intestinal) or external (perianal) autoinfection

A

True

72
Q

True or False: The rhabditiform larvae can either be passed in stool or cause autoinfection

A

True

73
Q

Where do the eggs of Strongyloides hatch into larvae?
A. Intestine
B. Colon
C. Liver

A

A. Intestine

74
Q

What are 2 features of Strongyloides life cycle that makes them more complex than other nematodes?

A
  1. Alternates between free living and parasitic life cycles
  2. Potential for auto-infection and multiplication within host
75
Q

How do you dx Strongyloidiasis?

A

Larvae (NOT EGGS!) in stool

  • No sx

Medical Microbiology (31 decks)

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