Ostertagia Flashcards
(29 cards)
Give the genus and species of the bovine equivalent of Teladorsagia
Ostertagia ostertagi
Ostertagia ostertagi are also known as?
The brown stomach worm
Where are Ostertagia ostertagi found in the body?
Abomasum
Which condition is caused by Ostertagia ostertagi?
Parasitic gastritis
Give some morphological features of Ostertagia ostertagi
- 1cm in length
- Slender
- Pinky brown colour
- Fine cervical papillae
- Males have a bursa and spicules
How can Ostertagia ostertagi be differentiated from other GI worms?
o Site in the abomasum
o Size – medium, not as big as Haemonchus and not as small as Trichostrongylus
o Fine cervical papillae on the anterior end of the worm
Describe the life cycle of Ostertagia ostertagi up to L3
- Direct, no immediate host
- Spread directly from one cow to another via free living stages on pasture
- L1-L3 is in faecal pat
- L3 is the infective stage
- L3 is ensheathed
How is L3 protected?
The L3 retains the cuticle of the L2 larvae so they are surrounded by a protective cuticle
Describe the eggs of Ostertagia ostertagi
90 x 45μm, barrel shaped, undifferentiated
How do the L3 of Ostertagia ostertagi develop and become infective?
- Cattle eat L3 as they graze
- L3 are swallowed and reach abomasum
- Burrow into the gastric glands and develop into L4 and L5
- L5 emerge into the lumen of the abomasum
- L5 mature to adults and lay eggs
What is the pre patent period?
The time taken from when the cow first ingests a larvae through detection of eggs in the faeces of that animal
How long is the pre-patent period for Ostertagi ostertagi?
3 weeks
In a PM, how would an infection of Ostertagia be identified?
White/cream nodules created by the developing larvae within the gastric glands
Describe the pathogenesis of Ostertagia damaging the gastric glands
- L4 and L5 develop in the gastric glands causing damage as the grow and feed
- The damaged cells are replaced by undifferentiated epithelial cells
- Loss of acid production causes an increase in abomasal pH
- Loss of bacteriostatic effect
- No conversion of pepsinogen to pepsin
- Increased permeability of the mucosa
What are the functions of the gastric glands?
- Maintains acid pH in abomasum
- Bacteriostatic
- Converts pepsinogen to pepsin
Which cells produce acid in the gastric glands?
Parietal cells
What are the clinical signs of a Ostertagia infection?
- profuse watery diarrhoea
- weight loss
- loss of appetite
Describe type 1 bovine ostertagiosis
- occurs in dairy replacement calves
- disease occurs in the summer (august)
- calves ingest large numbers of L3 in July
- green watery diarrhoea
- majority of calves in a group are affected
Describe type 2 bovine ostertagiosis
- yearling calves
- less common
- disease in late winter/early spring (january-march)
- acute disease
What are the clinical signs of type 2 bovine ostertagiosis
Intermittent diarrhoea, anaemia, thirst, weight loss
Do higher levels of mortality occur in type 1 or 2 bovine ostertagiosis?
Type 2
Define hypobiosis
The arrested development of L4 larvae within the host, in response to a trigger received by the free living L3
What is the trigger for hypobiosis?
Drop of ambient temperature in autumn
Do L3 hypobiose before or after they have been ingested?
After
