Parasitology Exam 2: Trematodes

Question 1

What is another name for trematodes?

Answer 1

Flukes

Question 2

Describe trematodes as a whole.

Answer 2

Platyhelminth (flatworm)
Dorsoventrally flattened
Most are hermaphroditic
Transmitted by ingestion of metacercariae (tailless encysted larvae)

Question 3

List in order, the 4 stages that most trematodes go through in their life cycle.

Answer 3

Egg –> miracidium (free swimming larva) –> redia (cylindrical larvae) –> cercariae (tailed larva) –> metacercariae (tailless larva)

Question 4

Name the intestinal trematodes:

Answer 4

F. buski
H. heterophyes
M. yokogawai

Question 5

Name the liver trematodes:

Answer 5

C. sinensis
F. hepatica

Question 6

Name the blood/body fluid trematodes:

Answer 6

S. haematobium
S. japonicum
S. mansoni

Question 7

Name the lung trematode:

Answer 7

P. westermani

Question 8

Which eggs are indistinguishable from F. buski?

Answer 8

F. hepatica

Question 9

What are the reservoir and definitive hosts of F. buski?

Answer 9

Reservoir: pigs, dogs, rabbits
Definitive host: pigs and humans

Question 10

How is F. buski transmitted?

Answer 10

Ingestion of raw water chestnuts or caltrop contaminated with infected feces

Question 11

What is the infective/diagnostic stage of F. buski?

Answer 11

Infective: ingestion of metacercariae on water chestnuts/plant

Diagnostic: eggs in feces

Question 12

How is H. heterophyes transmitted?

Answer 12

Ingestion of raw, pickled, or inadequately cooked fish

Question 13

What is the diagnostic/infective stage of H. heterophyes?

Answer 13

Infective: ingestion of metacercariae in undercooked fish
Diagnostic: eggs in stool

Question 14

Which eggs are H. heterophyes’ eggs indistinguishable from?

Answer 14

M. yokogawai

Question 15

What is the smallest human fluke?

Answer 15

M. yokogawai

Question 16

What is the most common intestinal fluke infection in the far east?

Answer 16

M. yokogawai

Question 17

How is M. yokogawai transmitted?

Answer 17

Ingestion of raw/undercooked fish

Question 18

What is the intermediate hosts of M. yokogawai and H. heterophyes?

Answer 18

snails and freshwater fish

Question 19

In which form are intestinal flukes accidentally ingested by humans?

Answer 19

Metacercariae

Question 20

Which is the chinese liver fluke? Which is the sheep liver fluke?

Answer 20

C. sinensis = chinese liver fluke
F. hepatica = sheep liver fluke

Question 21

Where do adult liver flukes live?

Answer 21

Biliary ducts

Question 22

How to prevent liver fluke infections?

Answer 22

Ensure that fish and aquatic vegetation are properly cooked

Question 23

What is the definitive and intermediate hosts of C. sinensis?

Answer 23

Definitive: humans
Intermediate: snails/fish

Question 24

Describe the life cycle of C. sinensis.

Answer 24

1. eggs ingested by snail
2. cercariae leave snail and enter water
3. cercariae penetrate fish
4. metacercariae develop in fish
5. undercooked fish consumed
6. metacercariae encyst in the duodenum and travel to bile duct to mature into adults

Question 25

What is notable about C. sinensis eggs?

Answer 25

HEAVILY shouldered operculum with a small knob at the end opposite of the operculum

Question 26

Lab ID of C. sinensis

Answer 26

Eggs in feces

Question 27

Describe the life cycle of F. hepatica

Answer 27

Miracidia invade a snail intermediate host Metacercariae on aquatic vegetation Humans ingest raw water chestnuts Metacercariae encyst in duodenum and into the peritoneal cavity

Question 28

Lab ID of F. hepatica

Answer 28

Eggs in feces

Question 29

What is special about F. hepatica eggs?

Answer 29

Operculated Indistinguishable from F. buski eggs Not as heavily operculated as C. sinensis

Question 30

Transmission of P. westermani?

Answer 30

Ingestion of uncooked crabs, crayfish, freshwater shrimp, mussels

Question 31

Describe the life cycle of P. westermani

Answer 31

Adult worms encapsulated in the lungs produce eggs Eggs coughed up and swallowed Excreted in feces Enter snail host Enter crab/crayfish Raw or undercooked crab/crayfish consumed

Question 32

Lab ID of P. westermani

Answer 32

ID of eggs in stool or sputum

Question 33

What is notable about eggs of P. westermani?

Answer 33

Operculated with shoulders Thick-shelled on the end opposite of the operculum

Question 34

What are Charcot-Leyden crystals?

Answer 34

Slender, pointed crystals made of an eosinophil protein that may be seen in sputum or lung tissue specimens of patients w/ parasitic infections Associated with P. westermani

Question 35

What is different about the blood/body fluid flukes from other flukes?

Answer 35

Adult schistosomes are NOT flattened Separate male and female worms present (NOT hermaphroditic)

Question 36

What organisms cause the disease schistosomiasis/bilharziasis/snail fever?

Answer 36

Schistosoma spp.

Question 37

How are Schistosoma spp. transmitted?

Answer 37

Fecal/urine contamination of small bodies of water that favor the growth of snail hosts

Question 38

What is different about the life cycle of Schistosoma from other flukes?

Answer 38

No encysted stage Infective stage is cercaria

Question 39

Which Schistosoma spp. causes urinary schistosomiasis?

Answer 39

S. haematobium

Question 40

Which Schistosoma spp. causes hepatointestinal disease (enlarged spleen and liver)?

Answer 40

S. japonicum

Question 41

Lab ID of Schistosoma spp.

Answer 41

ID of eggs in feces (S. japonicum/S. mansoni) ID of eggs in urine (S. haematobium)

Question 42

Differentiate the eggs between the Schistosoma spp.

Answer 42

S. haematobium egg: found in urine, terminal spine S. japonicum egg: found in stool, with a small inconspicuous lateral spine S. mansoni egg: LARGE lateral spine, found in stool