Parasitism Flashcards
(44 cards)
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
