6.11 Nematodes - Strongylids - Strongyles and Trichostrongyles Flashcards
(56 cards)
Trichostrongyles are a major threat to what animals
food production animals on pasture
what type of life cycle do Trichostrongyles have
direct (monoxenous)
what occurs regarding eggs/larvae of all Trichostrongyles
larvae develop to L3 in the eggs and hatch on pasture
what is the appearance of all Trichostrongyle eggs
thin shelled, morulated
what type of migration do Trichostrongyle L3 larvae do in the host? what are the implications
mucosal; no vertical transmission
what is the name for the medium-sized stomach worm of ruminants
Ostertagia/Teladorsagia
Ostertagia infects ___________ whereas Teladorsagia infects ___________________
cows; sheep and goats
how big are Ostertagia/Teladorsagia
up to 1cm
describe the life cycle of Ostertagia/Teladorsagia
larvae develop in eggs to L3 and hatch on pasture -> oral ingestion of L3 -> mucosal migration in the gastric pits
what is a major part of the epidemiology/pathogenesis of disease caused by Ostertagia/Teladorsagia
hypobiosis -> depends on environmental conditions on pasture
Does the pathogenesis of Ostertagia/Teladorsagia depend on larvae or adults? How?
larvae; they cause damage to the gastric glands and induce inflammation and hyperplasia
describe the pathogenesis of Ostertagia/Teladorsagia
- increased mucous production
- loss of function of parietal cells (less HCl) -> increased pH -> dysbiosis
- leakage through altered mucosa -> proteins, water, electrolytes to the lumen; pepsinogen to the blood
- altered protein metabolism -> emaciation
what are the gross lesions associated with Ostertagia/Teladorsagia
altered mucosa with single or coalesced nodules in the abomasum
describe the 3 distinct clinical presentations of Ostertagia/Teladorsagia and when you would expect to see them
Type 1: favorable pasture environment -> no hypobiosis -> infections in the SUMMER
Pre-Type 2: unfavorable pasture environment -> hypobiosis in the gastric glands
Type 2: reactivation of larvae in spring -> peracute infection in the SPRING
what is the name for the large stomach worm of ruminants? how big is it
Haemonchus; up to 3cm
what is the appearance of Haemonchus
barberpole
describe the life cycle of Haemonchus
larvae develop to L3 in eggs and hatch on pasture -> ingestion -> brief mucosal migration of L3s
both Ostertagia/Teladorsagia and Haemonchus have hypobiosis as a key factor in their epidemiology and pathogenesis; how are they different?
Ostertagia/Teladorsagia larvae and eggs survive well in pasture over the winter whereas Haemonchus larvae and eggs survive poorly in pasture over the winter
is the pathogenesis of Haemonchus associated with the larvae or adults and why
adults; blood-feeding on the mucosa in the abomasum
describe the pathogenesis of Haemonchus
anemia and hypoproteinemia; hemorrhage in the abomasum
what are the clinical signs of acute and chronic Haemonchus
Acute: profound anemia and hypoproteinemia -> pale carcass, edema, watery blood
Chronic: ongoing blood loss -> anemia and edema, muscle weakness and fat depletion, dark hard feces
what is the characteristic appearance of Nematodirus adults and eggs
adults often coiled together; can see eggs through the cuticle of adults; eggs can be seen grossly!
what Trichostrongylid parasite has eggs that can be seen grossly
Nematodirus
describe the life cycle of Nematodirus
larvae develop to L3 in eggs and hatch on pasture -> ingestion -> L3 develop between the villi of the small intestine -> adults in the lumen