Seminar 3: Trematodes

Question 1

Trematodes are parasititc _____

Answer 1

flatworms

Question 2

Most trematodes are hermaphroditic, but ____ is the exception

Answer 2

Schistosoma

Question 3

Schistosoma have oral suckers and the female can be found:

Answer 3

inside the male canal

Question 4

What are the 2 families of liver flukes?

Answer 4

Fasciolidae and opisthorchiidae

Question 5

Liver flukes cause:

Answer 5

liver, gallbladder, and bile duct disease

Question 6

Fasciola infects who? how?

Answer 6

humans and lifestock (sheep/ cattle/ goats)
- by ingesting the parasite on raw freshwater plants (watercress)

Question 7

The definitive host for Fasciola is

Answer 7

humans/ ruminants

Question 8

Explain the life cycle of Fasciola spp

Answer 8

a. unembroynated eggs are passed in feces
b. eggs become embryonated in water
c. miracidia hatch from eggs, seek out snail intermediate host to penetrate
d. In SNAIL tissue: sporocysts –> rediae –> cercariae
e. free-swimming cercariae encyst on aquatic veg.
f. metacercariae on veg ingested by definitive host (INFECTIVE STAGE)
g. immature flukes excyst in duodenum, penetrate intestinal wall, & migrate through liver to bile ducts where they become sexually mature
h. adult flukes in bile ducts –> lay eggs and passed in feces

Question 9

Why do fasciola cause so much damage?

Answer 9

they move THROUGH things, not around (they degrade tissue in guts etc)

Question 10

Fasciola are ___cellular

T/F they can create favorable enviros for themselves

Answer 10

extracellular: need to be able to evade immune response

true: can suppress inflammation in host

Question 11

Fasciola adults have which 2 structures to cause damage?

Answer 11

1. oral sucker: mouth for ingesting (at tip)
2. acetabulum: helps hold on (big blob near the top)

both are only in adults, not juveniles

Question 12

Human fascioliasis causes ____ problems

Answer 12

gastrointestinal
(b/c parasite in invading the gut wall)

• acute, latent, and chronic

Question 13

Eosinophilia=

Answer 13

a type of white blood cell that play a role in clearing out the infection

Question 14

Opisthorchis has 2 species infectious to humans:

Where are these present and how can you get them?

Answer 14

1. Opisthorchis viverrini
2. Opisthrochis felineus (aka cat liver fluke)

Present in SE Asia, Europe, Russia

Get from eating raw fish (only way). NOT from contaminated water/ plants

Question 15

Explain the Opisthorchis life cycle

Answer 15

a. embryonated eggs passed in feces
b. eggs ingested by snail
c. free-swimming cercariae encyst in the skin of freshwater fish
d. metacercariae in flesh of fish are ingested by human host
e. excyst in duodenum
f. go through liver to bile ducts: adults in bile ducts

Question 16

T/F
Opisthrochiasis symptoms are similar to schistosomiais

Answer 16

true

Question 17

Opisthorchiasis can cause cholangiocarcinoma (____ _____ _____)

Answer 17

bile duct cancer