Parasitism Flashcards
What are the four important internal parasites in grazing animals?
Nematodes
Liver fluke
Lungworm
Coccidia
What is the pre-patent period of a nematode?
21 days
Where do nematode larvae develop best?
Late summer/autumn
When warm and moist
What can nematode larvae survive?
Freezing
Not desiccation
What can affect husbandry in practices within the UK especially?
Changing weather patterns
Where are liver fluke eggs shed?
In faeces
Where does liver fluke have an intermediary stage of its life cycle?
In snails
How does liver fluke reenter the animal?
Metacercaria on vegetation gets eaten
When do we get acute signs of fluke?
Lots of immature flukes in the liver
Where is most of the nematode population?
Mostly on herbage
95% of larvae live in bottom inch
What percentage of animals pass the majority of the nematode eggs?
Small percentage - 20%
What is targeted collective treatment?
Treat the 20% of animals that are infecting the pasture rather than the whole herd
What is the succession of worm species in sheep?
Nematodirus battus Ostertagia Haemonchus Trichostrongylus Fluke
What can cause sudden death of lambs in spring?
Nematodirus battus
Become sensitized to cold weather and hatch as soon as it becomes warmer
What does haemonchus look like?
Barber pole - ingest blood
When does fluke begin to kick in?
End of grazing period
Why are GI parasites a problem for farmers?
Cause production loss
Costs in controlling outbreaks
What are the three types of worm you can find in the abomasum?
Haemonchus
Ostertagia
Trichostrongylus
What is the equivalent parasite to Ostertagia in sheep?
Teladorsagia
What are the clinical signs of nematode infection?
Diarrhoea
Weight loss
Death
What is the main sub-clinical sign of nematode infection?
Reduced weight gain
Less than Optimal Productivity
How do nematodes cause weight loss?
Reduced appetite - eat less dry matter Change in gut structure/function Immune and inflammatory responses Malabsorption Energy cost of immune response
What are four causes of protein loss in parasitic gastroenteritis?
Increased secretion of mucous and IgA
Increased mucosal permeability allowing leakage
Increased cell turnover in mucosa
Local antigen/antibody reaction in gut
What may sub-clinical production losses arise from?
Continuous low-level exposure of susceptible animals to infectious helminth larvae
What can haemonchus cause?
Anaemia
What is a FAMACHA test?
Colour chart held up alongside eye to determine anaemia status
What is seen with chronic liver fluke?
Blood and protein loss
Hyperplasia of bile ducts
Poor productivity
What are the harmful effects of parasites in growing animals?
Reduced weight gain
Poorer feed conversion ratio
Anaemia
Death
What are the harmful effects of parasites in adult animals?
Weight loss
Poor BCS
Decreased reproductive performance
Decreased milk/wool production and performance
What are the four situations where there isn’t a good immunity in adults?
Goats
Immuno-compromised
Ewes after lambing (post parturient relaxation in immunity)
Liver fluke
What animals are present and what is the weather like in spring?
New crop of young animals
Weather warming up and moist
What are the two sources of parasites on pasture in the spring?
Over wintered - major source
From adults
What are the two main parasite threats in spring?
N. battus
Type 2 osteragia
What occurs in summer in regards to parasites?
Larval numbers increase
Liver fluke eggs begin to hatch
What is the main parasite threat in the summer?
Nematodes
Telodorsagia in lambs/goats
What are sub-clinical effects usually seen in the summer?
PGE
Bovine ostertagiosis
What season does the peak in pasture larva level?
Autumn
What is the main parasite threat in autumn?
Trichostrongylus
When is larval development halted?
Winter
What three things interact to bring about disease?
Host
Environment
Parasite
What is the main objective of control of endoparasites?
Limit exposure of susceptible animals to large numbers of larvae
What is the auto-infection peak?
Animals are being contaminated with larvae that they passed themselves
What do we use to break parasites life-cycle?
Anthelmintics
What is a pretty safe pasture?
Pasture used after the hay/silage has been cut
Graze with animals that don’t carry parasites
Long grass to dilute effect
