Trematodes

Question 1

Describe the life cycle of liver fluke

Answer 1

1. Adults in bile ducts lay eggs
2. Eggs excreted in faeces
3. Eggs hatch to miracidium after 2-4 wks in presence of water
4. Miracidium infect mud snail (

Question 2

In what species is acute disease commonly seen in?

Answer 2

Sheep

Question 3

What are the clinical signs of acute disease and what are they attributed to?

Answer 3

Submandibular oedema, weight loss.

Migration of juveniles through liver parenchyma.

Question 4

At what time after infection is acute and chronic disease seen?

Answer 4

Acute 2-8 wks, chronic 8-12 wks

Question 5

What are the clinical signs of chronic disease and what are they attributed to?

Answer 5

Cachexia, anaemia, depression, submandibular oedema.

Adults in bile duct.

Question 6

How is liver fluke diagnosed?

Answer 6

FEC (>8 weeks post infection)
ELISA for coproantigen, Ab
Increased liver enzymes (GGT = bile duct damage, GLDH = parenchyma damage)

Question 7

How can grazing be managed to reduce fluke incidence?

Answer 7

Fence off wet/boggy areas
Move off high risk pasture in August
Avoid high risk pasture if possible
Graze cattle on high risk pasture for 8 wks then treat and move to fresh pasture

Question 8

How is liver fluke treated?

Answer 8

BZD - Nitroxynil, Closantel (Triclabendazole = resistance)
Remove adults at key times to reduce pasture contamination
Treat every 8 wks in high risk areas?

Question 9

How are animals treated for fluke at housing?

Answer 9

Treated at housing and then 8wks later

Question 10

How does the lifecycle of Dicrocoelium dendriticum differ from Fasciola?

Answer 10

2 IMH - snail and an ant

Cercaria enters mesenteric ganglion on ant, climbs to top of grass stalk, higher chance of being ingested

Question 11

Describe the lifecycle of rumen fluke (Calicophoron daubneyi)?

Answer 11

1. Adults lay eggs which are excreted in the faces
2. Eggs hatch and immature larvae infect snails
3. Larvae develop in snail and emerge in the slime
4. Metacercaria encyst on grass and are ingested
5. Excyst in the duodenum where immature stages feed (causes severe blood and fluid loss)
6. Juveniles migrate towards the rumen as they mature
7. Adults feed in the rumen and cause minimal pathology

Question 12

How is rumen fluke diagnosed?

Answer 12

FEC

Question 13

How is rumen fluke treated?

Answer 13

Oxyclozanide off license (Zanil, Levafos)