Introduction/Telodorsagia Flashcards
Define parasite
An organism that is dependent metabolically on another, where one organism benefits at the expense of another
What are the three major groups of parasites?
Helminths, Protozoa, Arthropods
What are helminths?
Nematodes and worms
What are examples of arthropods?
insects, arachnids
Describe a nematodes structure?
roundworms, cylindrical, range of sizes, both free living and parasitic, often with specific heads/tails
What is the basic anatomy of a nematode?
Cuticle outer layer, followed by hypodermic, muscle cells, containing fluid filled cavity- gut runs inside full length,
What different organs do male and female nematodes possess?
Females- ovary, uterus, vulva
Males- testis, vas deferens, cloaca
What are the different organs of a nematodes digestion system?
Mouth, buccal cavity, oesophagus, intestine, anus
In general which sex of nematode is larger?
Females
What are the two predominant species of nematodes which cause PGE?
Telodorsia circumcincta and trichostronglyus spp
What is PGE?
Parasitic gastroenteritis
Which species of Nematodes are found in the small intestine of sheep?
Cooperia spp, trichostrongylus
Which species of nematodes are found in the abomasum of sheep?
telodorsagia circumcincta
trichostrongylus axei
Name the species of nematodes found in large intestines of sheep?
Chabertia spp, oespgagostomum spp, trichuris spp
Why is the location of a nematodes within the GI tract important?
Important for identification and pathology
Where is teladorsagia circumcinta found in sheep?
Abomasum
What disease does toladorsagia circumcinta cause individually, and then with other parasites?
Parasitic gastritis by itself
PGI with other parasites
What is the problem with sheep being infected with telodorsagia circmcinta?
Limits productivity and welfare
Describe the morphology of telodorsagia circumcincta
Slender, pinky brown worm, fine cervical papillae at head end in both sex
What extra organs do male telodorsagia circumcinta posses?
Bursa and spicules
Why is telodorsagia circumcinta described as direct?
No intermediate host
Describe telodorsagia circumcinta eggs?
Barrel shaped, contain undifferentiated morula
What is the life cycle of telodorsagia circumcinta?
1- larvae (L1) develops in egg
2- L1 hatches and feeds on faecal pat
3- Grows and moults to L2
4- Repeated to L3- L3 ensheathed
5- L3 released from faecal pat by rain splash
6- L3 infective stage on grass
7- Sheep eats L3 during grazing
8- burrows into gastric glands
9- develops into L4 and L5
10- L5 immature and emerges into lumen of abomasum
11- Matures to adult, mates and lays eggs
What is the pre-patent period?
Patency is when the parasite reaches maturity and can be detected- producing eggs- therefore time from infection to patency
What is the pre-patent period of telodorsagia circumcinta?
3 weeks
What is the rate of development from eggs to L3 dependent on in telodorsagia circumcinta?
Temperature dependent
What is parasitic gastro-enteritis associated with?
Large numbers of larvae- 40,000
Why do telodorsagia cicumcinta cause deficit in protein?
Damage to gastric glands from developing and emerging L5 larvae, gastric glands contain acid producing parietal cells, therefore ph not maintained and pepsinogen to pepsin doesn’t occur
What is the difference between type 1 and 2 parasitic gastro-enteritis?
Type 1 is in first season grazing lambs where as type 2 is in yearling animals from hypobiosed larvae
What are the clinical signs of parasitic gastro-enteritis?
Profuse watery diarrhoea, weight loss, inappetence, dehydration, death
What are the sub-clinical signs of parasitic gastro-enteritis?
Poor weight gain, reduced appetite, reduced feed intake, loss of plasma proteins
When does type 2 parasitic gastro-enteritis occurs and why?
Late winter/early spring due to hypobiosed larvae
What is hypobiosis and why does it occur?
Arrested development of larvae within host in response to trigger received by free living L3
Trigger drop in temperature
Therefore L3 hypobiose when ingested
What endoparasites are found in the large intestine?
COT
Chabertia
Oesophagstomum
Trichuris
What endoparasites are found in the small intestine?
NTC
Nematodirus spp
Trichostronglyus spp
Cooperia
What endoparasites are found in the abomasum?
HTT
Haemonchus contortus
Telodorsagia circumcinta
Trichostrongylus axei
