08. Intestinal trematodes Flashcards

1
Q

Is Fasciolopsis buski large or small?

A

large intestinal fluke

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2
Q

Is Heterophyes large or small?

A

small intestinal fluke

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3
Q

Is Metagonimus large or small?

A

small intestinal fluke

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4
Q

Is Echinostoma large of small?

A

small intestinal fluke

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5
Q

name three intestinal/digestive tract flukes

A
  • Fasciolopsis buski
  • Heterophyes heterophyes
  • Metagonimus yokogowi
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6
Q

What is the largest intestinal fluke of humans?

A

Fasciolopsis buski

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7
Q

Where is Fasciolopsis buski common?

A

Asia and the Indian subcontinent - especially in the areas where humans raise pigs and consume freshwater plants

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8
Q

what is the common name for Fasciolopsis buski?

A

giant intestinal fluke

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9
Q

what is the DH of Fasciolopsis buski?

A

humans, dogs, pigs, rabbits

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10
Q

what is the first IH of Fasciolopsis buski?

A

water snail

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11
Q

what is the second IH of Fasciolopsis buski?

A

aquatic vegetation

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12
Q

what is the infective stage of Fasciolopsis buski?

A

encysted metacercariae

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13
Q

what is the diagnostic stage of Fasciolopsis buski?

A

eggs in feces

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14
Q

what is the size of Fasciolopsis buski?

A

length: 20-75mm
width: 20mm

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15
Q

which adult worm is Fasciolopsis buski similar to?

A

Fasciola hepatica

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16
Q

what is the difference in the life cycle of Fasciolopsis buski and Fasciola hepatica?

A

the adults inabit the intestinal tract rather than the liver

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17
Q

what are the common reservoir hosts for Fasciolopsis buski

A

dogs and pigs

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18
Q

what happens to Fasciolopsis buski after ingestion by the DH

A

the metacercariae excyst in the duodenum and attach to the intestinal wall

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19
Q

what happens when the metacercariae of Fasciolopsis buski excyst in the duodenum of the DH?

A

There they develop into adult flukes (20-75mm by 8-20mm) in approx.. 3 months, attached to the intestinal wall of the mammalian hosts (humans and pigs)

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20
Q

describe the life cycle of Fasciolopsis buski

A

1- Unembryonated eggs passed in feces
2- Embryonated eggs in water (embryonate in water)
3- Miracidia hatch, penetrate snail
4- Snail
a. Sporocyst
b. Rediae
c. Cercariae (shed from the snail into the environment)
5- Free-swimming cercariae
6- Metacercariae on water plant ingested by humans or pigs causing infection
7- Excyst in the duodenum
8- Adults in the small intestine

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21
Q

What are human infections of Fasciolopsis buski associated with?

A

Human infections are associated with eating metacercariae encysted on freshwater vegetation

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22
Q

what are common plants to be infected by the encysted metacercariae of Fasciolopsis buski?

A
  • Common plants: are lotus roots, bamboo shoots and water chestnuts
  • In regions in southeast Asia, this is common to eat and if it is not cooked properly you can become infected with F. buski metacercariae
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23
Q

what are the symptoms of infection with Fasciolopsis buski?

A
  • Outward signs of infection are usually the abdominal symptoms (discomfort, nausea, diarrhea) associated with the inflammation of the gut wall caused by the presence of the parasite
  • large numbers of flukes may obstruct the flow of the intestine
  • Infected individuals may also suffer an immune sensitization caused by the foreign proteins present in the parasite, which presents as fluid build-up (oedema) in the face, abdomen and lower limbs. This occurs in rare cases
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24
Q

how is Fasciolopsis buski diagnosed?

A
  • Microscopic identification of eggs from the feces

- These cannot be distinguished from Fasciola hepatica (unembryonated with distinct operculum)

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25
Q

what is Heterophyes heterophyes?

A

a very small intestinal fluke

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26
Q

what is the common name of Heterophyes heterophyes?

A

small intestinal flukes

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27
Q

what is the DH of Heterophyes and heterophyes?

A

humans, dogs, cats, birds (carnivores - eating fish that is not properly cooked or smoked)

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28
Q

what is the first IH of Heterophyes heterophyes?

A

fish

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29
Q

what is the infective stage of Heterophyes heterophyes?

A

encysted metacercariae

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30
Q

what is the diagnostic stage of Heterophyes heterophyes?

A

eggs in feces

31
Q

What is the morphology of the eggs of Heterophyes heterophyes?

A
25-30x15-17µm
yellow-brown color
tick egg shell
inconspicious oprculum
embryonated (miracidium inside)
32
Q

describe the life style of Heterophyes heterophyes

A

1- Embryonated eggs each with a fully-developed miracidium are passed in feces
2- Snail host ingests eggs, miracidia emerge from eggs and penetrate the snail’s intestine (a, b, c in snail tissue)
a. Sporocysts
b. Rediae
c. Cercariae
3- Cercariae released for snail
4- Cercariae penetrate the skin of fresh/brackish water fish and encyst as metacercariae in the tissue of the fish
5- Host becomes infected by ingesting undercooked fish containing metacercariae
6- Metacercariae excyst in the small intestine
7- Adult in small intestine

33
Q

How can the DH become infected?

A

The definitive host becomes infected by ingesting undercooked or salted fish containing metacercariae

34
Q

What happens after ingestion of the metacercariae of Heterophyes heterophyes? who ingests these?

A

the DH host ingest the metacercariae

After ingestion, the metacercariae excyst, attach to the mucosa of the small intestine and mature into adults (measuring 1.0 to 1.7mm by 0.3-0.4mm)

35
Q

how is the diagnosis done for Heterophyes heterophyes?

A

microscopic identification of eggs from the feces

the eggs are indestinguishable from those of Metagonimus yokogawai and resemble those of Clonorchis and Opisthorcis

36
Q

what is Metagonimus yokogawai?

A

a very small intestinal fluke?

37
Q

what is the common name of Metagonimus yokogawai?

A

small intestinal fluke

38
Q

what is the habitat of Metagonimus yokogawai?

A

small intestine

39
Q

what is the definitive host of Metagonimus yokogawai?

A

humans, dogs, cats, canines

40
Q

what is the first IH of Metagonimus yokogawai?

A

water snail

41
Q

what is the second IH of Metagonimus yokogawai?

A

fish

42
Q

what is the infective stage of Metagonimus yokogawai?

A

encysted metacercariae

43
Q

what is the diagnotic stage of Metagonimus yokogawai?

A

eggs in feces

44
Q

what shape is the egg of Metagonimus yokogawai?

A

ovoid

45
Q

what is the morphology of the egg of Metagonimus yokogawai?

A

yellow-brown color
thick egg shell
inconspicuous operculum
embryonated (miracidium inside)

46
Q

how does the DH become infected with Metagonimus yokogawai?

A

by ingesting undercooked or salted fish containing metacercariae

47
Q

other than humans, which fish-eating mammals and other fish-eaters, can become infected by Metagonimus yokogawai?

A

cats and dogs, and birds

48
Q

describe the life cycle of Metagonimus yokogawai

A

1- Embryonated eggs each with a fully-developed miracidium are passed in feces
2- Snail host ingest eggs, miracidia emerge from eggs and penetrate the snail’s intestine
3- Cercariae released from snail
4- Cercariae penetrate the skin of fresh/brackish water fish and encyst as metacercariae in the tissue of the fish
5- Host becomes infected by ingesting undercooked fish containing metacercariae
6- Metacercariae excyst in the small intestine
7- Adult in small intestine
8- Fish-eating mammals and birds can be infected as well (back to 1 in feces)

49
Q

what happens when the Metagonimus yokogawai goes to the mucosa of the small intestine (pathology)

A

inflammation

50
Q

where can the eggs migrate to other than the small intestine?

A

heart, brain

51
Q

how is Metagonimus diagnosed?

A
  • microscopid identificaton of the eggs
  • The eggs are indistinguishable (somewhat) from those of Heterophyes heterophyes and resemble those of Clonorchis and Opisthorchis
  • Specific diagnosis is based on identificstion of the adulk fluke evacuated after anthelminthic therapy, or found at autopsy
52
Q

what two parasites have the following in common:

- life cycle, pathology, diagnosis, and treatment

A

Metagonimus yokogawai and Heterophyes heterophyes

53
Q

what is the geographic distribution of Echinostoma?

A

worldwide

54
Q

what is the common name of Echinostoma?

A

spiny fluke

55
Q

what is the habitat of Echinostoma?

A

small intestine

56
Q

what is the DH of Echinostoma

A

human, aquatic bird

57
Q

what is the first IH of Echinostoma?

A

water snail

58
Q

what is the second IH of Echinostoma?

A

clam, snail, leech, fish, or tadpole

59
Q

what is the infective stage of Echinostoma?

A

encysted metacercariae

60
Q

what is the diagnostic stage of Echinostoma?

A

eggs in feces

61
Q

what is the disease caused by Echinostoma?

A

Echinostomiasis

62
Q

what is observed on the eggs of Echinostoma?

A

an inconspicuous operculum

63
Q

how are eggs of Echinostoma passed?

A

unembryonated in feces

64
Q

describe the life cycle of Echinostoma

A
1-	Unembryonated eggs passed in feces 
2-	Embryonated eggs in water 
3-	Miracidia hatch/penetrate snail
4-	In snail tissue
a.	Sporocyst 
b.	Rediae 
c.	Cercariae 
5-	Free-swimming cercariae invade second intermediate host 
6-	Metacercariae in second intermediate host; eaten by humans, aquatic birds, etc. 
7-	Excyst in duodenum (bird/human)
8-	Adults in small intestine
65
Q

Echinostoma life cycle is similar to _____ except ______

A

Fasciolopsis; the metacerrcariae excyst in various snails, tadpoles, freshwater fish

66
Q

describe the pathology of Echinostoma

A
  1. Found in the duodenum and jejunum of the small intestine. Causes a chronic inflammation
  2. Catarrhal inflammation often occurs due to the penetration of the sharp-spined collar into the intestinal mucosa
  3. In heavy infections, nausea, vomiting, diarrhea, fever and abdominal pain may occur
  4. Parasite is never life-threatening
67
Q

How is Echinostoma diagnosed?

A

microscopic identification of eggs from the feces

Because the eggs are large, careful measurements must be taken to avoid confusion with the eggs of Fasciola of Fasciolopsis. Species-level identification cannot be done based on egg morphology and adults are needed for a definitive diagnosis

68
Q

what is the treatment for Echinostoma?

A

praziquantel

69
Q

what are the two freshwater flukes? (Lac st. Louis)

A
  • Neascus spp. (black spot disease)

- Clinostomum spp. (yellow scrube)

70
Q

What disease comes about from Neascus spp.? what is this?

A

black spot disease

  • Ironically, theyre actually white. Dark pigment from where the fish encysts the flukes, making them look black.
  • Definitive hosts are kingfishers, loons, etc.
  • Adult worms live in the loon’s mouth where they produce eggs.
  • The eggs are swallowed by the bird, pass through it’s digestive system unharmed and are released into the water with the loon’s feces
  • The eggs hatch and enter aquatic sails
  • After maturing, they leave the snails and infect fish
71
Q

what is the yellow or white grub?

A

Clinostomum spp.

72
Q

where does Clinostomum spend most of its life?

A

in the mouth of herons

73
Q

what does Clinostomum do after leaving the heron?

A

invades snails and eventually a particular species of snail. Next it burrows into the muscle of a fish