Trematodes and cestodes of ruminants

What types of life cycles do flukes and tapeworms have?

indirect involving intermediate hosts

What phylum and class are flukes and tapeworms part of?

phylum platyhelminthes

class trematode (fluke)

class cestoda (tapeworms)

What are the two types of liver fluke? What is the scientific name of rumen fluke?

fasciola hepatica (common liver fluke)

decrocoelium dendriticum (lancet/tea leaf fluke way less common)

rumen fluke is calicophoron daubneyi

What type of reproducer is the liver fluke?

hermaphrodite so clonal reproduction in intermediate host, a mud snail

25000 eggs a day

What is the lifecycle of the liver fluke?

What is the temperature range that fluke eggs need to develop?

minimum 10 degrees to 25 degrees celsius

What is the temperature range that a cercarium needs to encyst in the pasture?

10-25 degrees celsius again

What is excystation?

“hatches" in the GI tract of the animal

What is peregrination?

the migration

they pass through the gut wall and enter the abdominal cavity

travel along inner surface of abdominal wall

reach diaphragm, against which lies the ventral lobe of the liver

juvenile fluke penetrate the diaphragmatic surface of the liver capsule

What does acute fasciolosis cause in sheep?

liver is easily damaged

high numbers of migratory juveniles cause parenchymal damage

hemorrhage within liver tissue

damage to larger blood vessels can cause catastrophic intra-abdominal hemorrhage

What is the timeline for acute fasciolosis?

week 1 to 8

At what point is it considered chronic and what are signs?

past the 12 week phase

cachexia

anemia

depression

What does the gross pathology of chronic liver fluke in cattle look like?

What is the pathophysiology of liver fluke?

feeding of flukes- hemorrhage/anemia

anorexia- reduced food intake

liver damage and dysfunction- diverse effects

immunomodulation- bacterial co-infection, TB diagnostics (can get false positive and negatives if they have fluke as well)

What are the major effect on performance of liver fluke at the different stages?

When does the peak challenge from fluke occur?

autumn from the metacercariae

What are the different methods of fluke diagnostics?

parasite, immunity, pathophysiology, pathology

What animals do the new lateral flow testing kits aim to test?

sentinel animals

ie in autumn for that year’s lambs or calves

What are different control measures?

grazing management: avoid grazing high risk pastures, selective grazing in endemic regions

snails: drainage, fencing

flukicides: strategic (pasture contamination), therapeutic (animal welfare and performance)

What is the spectrum of activity for each flukicide?

What is the rationale for using flukicides therapeutically?

remove adult fluke to limit damage to host

no need to use triclabendazole for a case like this

What is the rationale for using flukicides strategically?

remove adult fluke at key times to limit pasture contamination with fluke eggs

mainly beef because it’s difficult in adult dairy except spring-calving herds

How do you monitor fluke outbreaks?

bulk fecal eggs

What are the different options for winter treatments if housed? There are two options for different drugs.

When should flukicide treatment be given if the cattle is housed over winter? What about if out-wintered?

should be given about 8 weeks after turnout

out-wintered: flukicide treatment should be given about 8 weeks after the previous treatment

What flukicides can be used in milking cows?

oxyclozanide

albendazole

What are the obstacles to fluke control?

no natural immunity

practical limitations on ‘environmental’ control

flukicides- limited product range for juvenile fluke, withdrawal periods restrictive, limited options for rumen fluke

treatment recommendations- limited evidence base, co-infections, limited diagnostics

What is the treatment for dicrocoeliosis in sheep?

nothing registered, but albendazole at 15-20 mg/kg

How does the clinical disease of rumen fluke manifest?

typically affected animal showing diarrhea, dehydration, and poor condition

What would you find on necropsy on rumen fluke?

duodenum showing marked reddening with immature flukes (resembling bubbles) on the mucosa

immature rumen fluke in the duodenal lumen showing the acetabulum (oral sucker) surrounding a plug of duodenal mucosa

How do you control rumen fluke?

epidemiological overlap with liver fluke- snail habitats, sheep and cattle

treatment (off-label): oxyclozanide

Here’s a chart with all the ruminant cestodes

What is the life cycle for monieza expansa?

one intermediate host

How do you control tapeworms?

ruminants: albendazole, fenbendazole, ricobendazole, praziquantel + levamisole

dogs: praziquantel produces, exclude dogs from fields with sheep or cattle