Trematodes & Cestodes of Ruminants Flashcards
what are the taxonomy of helminths
nemathelminthes (roundworms)
- class nematoda
platyhelminthes (flatworms)
- class trematoda (fluke)
- class cestoda (tapeworms)
what are trematodes of ruminants
- liver fluke
- fasciola hepatica (common liver fluke)
- dicrocoelium dendriticum (lancet/tea leaf fluke)
- rumen fluke
* calicophoron daubneyi
what is the lifecycle of Fasciola hepatica
Eggs passed in feces and hatch as and develops into motile miracidium which infects the mud snail and undergoes clonal reproduction
Mobile cercaria hatch out of the snail and encyst as metacercariae which can survive on grass for several months which are eaten by the ruminan
how do eggs develop into miracidium in Fasciola hepatica
Fluke eggs passed in feces —> 10-25ºC —> embryo nation >2 weeks, temperature dependent
Hatching: moisture, no dung —> miracidium emerges from egg
what is the IMH of fasciola hepatica
galba truncatula
how does fasciola hepatica develop in the snail
Miracidium burrows into the snail and undergoes clonal reproduction for about > 6 weeks and forms a Cercarium
Cercarium needs about 10-25ºC where they lose their tail and encyst on vertical surfaces (vegetation) and become non motile metacercariae
how does excystation occur in fasciola hepatica
CO2 & temperature of ~39ºC
Pepsin in abomasum; trypsin in the duodenum
Glycocholic acid in the bile
how does pregrination occur in Fasciola hepatica
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 occurs from week ~1 to ~8 in parenchyma that causes acute fasciolosis in sheep
High numbers (>1000) of migratory juveniles
Parenchyma damage
Hemorrhage within liver tissue
Damage to larger blood vessels can cause catastrophic intra-abdominal hemorrhage
does acute fascioosis occur in cattle
very rare
Limited effects on performance in cattle are within first 8 weeks of infection
Major effects associated with bile duct colonization
what occurs in week 8 to 12 in the bile ducts of fasciola hepatica
Pre-patent period: 12 weeks
1 fluke can lay 25,000 eggs/day
what does chronic fasciolosis in sheep look like
cachexia
anemia
depression
what is the gross pathology of fasciola hepatica in cattle
enlarged bile ducts
enlarged gall bladder
fibrosis
does fasciola hepatica affect calf performance
Don’t start to see a decrease in performance until around week 8 when they start blood feeding in the bile ducts and they start to loose weight
what does fasciolosis cause in high yielding dairy herds
High levels of exposure associated with 15% lower milk yield
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
- Clostridium novyi
- Salmonella dublin
- Mycobacterium bovis
TB diagnostics
what are the infection patterns of fasciola hepatica
fection patterns:
Untreated stock carrying infection over winter and pass eggs out in the summer
These eggs will develop and infect during the summer —> rapid increase in infective metacercariae due to high temperatures which leads to a peak of infective capability in autumn
Snails that are infected can carry infection over the winter and can spread infective metacercariae in the spring
what are the seasonal trends in fluke diagnosis in sheep
Tend to see a peak in acute liver fluke in sheep in the autumn and second half of grazing season
Chronic liver fluke will build up throughout the winter and can be diagnosed any time but it is mainly a late winter disease
Rumen fluke is all year round and an increase in late winter
how is fluke diagnosed
how is Coproantigen used to diagnose fluke
ELISA test on feces to look for feeding flukes in bile ducts
Can pick up infection earlier than FWEC
But the sensitivity and specificity is not perfect —> better in sheep than cattle
how is Immune response used to diagnose fluke
Immune response but not an effective against infection
Presence of antibodies show that the animal has been exposed —> doesn’t show that it is a current infection
Rising plane in antibodies might suggest an increase in exposure
Or naive youngstock that have antibodies —> treatment protocols
how can GLDH and GGT be used to diagnose fluke
Liver function & damage
GLDH = glutamate dehydrogenase (liver parenchyma)
GGT = gamma glutamyl transferase (bile duct)
what are performance indicators of fluke
ADG
Milk yield
But can’t use this for a targeted selective treatment approach
Careful with differentials for ill thrift
what are control measures of flukes
grazing management
snail prevention
flukicides
how can flukes be managed by grazing management
Avoid grazing high risk pastures
Selective grazing in endemic regions
If farm has both high and low risk grazing
- Move stock off high risk pastures in August
- Graze cattle on high risk pastures for 8 weeks then treat (& move?)
how can flukicides be used to manage flukes
Strategic (pasture contamination)
Therapeutic (animal welfare and performance)
what are the flukicide spectrum of activities
Triclabendazole:
Effect on all stages
Reduce the risk of acute fluke or treat if it has emerged
Resistance developing
Avoid unnecessary use
what is the rationale for therapeutic flukicide treatment
Remove adult fake to limit damage to host
what is the rationale for strategic flukicide treatment
Remove adult fluke at key times to limit pasture contamination with fluke eggs
Mainly beef, difficult in adult dairy except spring calving herds
what are housing/winter therapeutic treatments for flukes
Therapy (cattle not to be grazed again)
Any effective flukicide at housing
May need to re-treat if high % of juvenile fluke?
Monitor: DLWG (bulk fecal eggs?)
what are housing/winter strategic treatments for flukes
*Fecal egg count to determine efficacy and/or need for treatment
what are strategic treatments for fluke at grazing
To limit fluke egg output in grazing stock up to July by removing any egg-laying adult fluke
what are obsticles to fluke control (4)
- no natural immunity
- practical limitations on ‘environmental’ control
- flukicides
- treatment recommendations
what are the practical limitations on environmental control of flukes
Drainage & fencing impractical and expensive
Snail habitats widespread
Population dynamics and dispersal of snails
Domestic livestock and wildlife reservoirs
what flukicide products can be used in dairy cows
what can be used to treat dicrocoeliosis in sheep
albendazole at 15-20 mg/kg
how is rumen fluke diagnosed
Diagnosed (FEC, abattoir) with increased frequency in UK & Ireland ~5 years
what is the intermediate host of rumen fluke
Galba truncatula
what are annual patterns of fluke diagnosis in cattle
what is the clinical disease of rumen fluke
typically affected animal showing diarrhea
dehydration
poor condition
where does rumen fluke cause pathology
duodenum
how is rumen fluke controlled
Epidemiological overlap with liver fluke
Snail habitats
Sheep and cattle
how is rumen fluke treated
Oxyclozanide (Levafas; Zanil)
12.8-18.7 mg/kg once or twice 3 days apart
what are important ruminant cestodes
what are the indirect life cycle of Moniezia expansa
one intermediate host oribatid mites
