6.11 Nematodes - Strongylids - Strongyles and Trichostrongyles Flashcards
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
is there hypobiosis with Nematodirus? why or why not
no - the larvae and eggs survive on pasture during the winter so it is not needed
what is the pathogenesis of Nematodirus
adults cause villous atrophy
what are the clinical signs of Nematodirus
diarrhea, anorexia, weight loss (due to the villous atrophy)
what is the name for the small stomach worm of ruminants
Trichostrongylus
what are the following:
- small stomach worm
- medium stomach worm
- large stomach worm
- small: Trichostrongylus
- medium: Ostertagia/Teladorsagia
- large: Haemonchus
what is the name for the red stomach worm of swine
Hyostrongylus rubidus
what group of parasites constitutes the largest single cause of colic insurance claims in horses
Strongyles
where do adult Strongyles live in horses
cecum and colon
how do we divide the Strongyles group
into migratory (Strongylus) and non-migratory (Cyanthostomes)
how do we tell apart different adult Strongyles - give examples
by the shapes of the buccal cavity
Strongyles: deeper than wide
Cyanthostomes: wider than deep
what is the general life cycle of the Strongyles
Larvae develop to L3 in eggs and hatch on pasture -> ingestion of L3s -> either extra-intestinal migration (Strongylus) or mucosal migration (Cyanthostomes) -> adults feed in cecum and colon
is there hypobiosis in the Strongyles
in some species (Cyanthostomes); some species can overwinter as larvae on pasture
what causes the pathogenesis associated with Strongylus vulgaris? is this adults or larvae?
developing larvae moving extra-intestinally in the cranial mesenteric artery -> arteritis and thrombosis
why do we not see pathogenesis associated with adult Strongylus vulgaris
insufficient adults to cause lesions due to feeding -> the larvae cause such an intense infection the animal dies from that first
what are the clinical signs of acute and chronic Strongylus vulgaris
acute: arteritis gives rise to pyrexia, anorexia, colic and death
chronic: intermittent colic
what are the names of the Strongylus spp. in horses
Strongylus vulgaris
Strongylus edentatus
Strongylus equinus
is the pathogenesis of Strongylus edentatus and Strongylus equinus associated with larvae or adults?
adults -> feeding on blood and mucosa
note: heavy infection will produce hemorrhage and inflammation in the colon when larvae re-enter the GI tract after their migration
how many species of Cyanthostomes exist in the horse and what are the implications
over 40+; different facilities will have their own ‘collection’ and moving the horse can result in infection as an adult from encountering new species
what is the general life cycle of the cyanthostomes
L3 develop in eggs on pasture -> ingestion of L3 -> mucosal migration -> hypobiosis in the mucosa in some species (some species overwinter as larvae on pasture)
Is the pathogenesis of Cyanthostomes associated with the larvae or adults and why
larvae -> mucosal migrations
describe the pathogenesis of Cyanthostomes
nodule formation around larvae -> inappetence and poor gastric motility -> poor weight gain
inflammation, edema and ulceration from larvae leaving the nodules
what are the clinical signs of Cyanthostomes
weight loss, anorexia, diarrhea, colic
end of Cyanthostomes hypobiosis in spring gives rise to
acute larval cyanthostomiosis
what are the clinical signs of large adult burdens of cyanthostomes
unthriftiness, colic
when should you not de-worm for Cyanthostomes and why
mid-winter; will kill larvae in situ and result in inflammation
what is the name of Gapeworm and what species does it affect
Syngamus trachea ; birds
describe the adult Syngamus trachea
males smaller than females; in copula entire life; y shaped structure attached to the trachea
describe Syngamus trachea eggs
- operculate on each side
- elongate, ellipsoidal and smooth
- morulated
describe the Syngamus trachea life cycle
larvae develop from morulated eggs and some hatch on pasture -> ingestion of eggs, larvae or a paratenic host -> migration to the lungs -> rupture alveoli and migrate to trachea -> attach to mucosa, mate, and suck blood
what is the PPP of Syngamus trachea
10 days
what are the clinical signs of Syngamus trachea
gaping/gasping; increased mucus; mild anemia; reduced production; mortality
what is the name for the Pimply gut worm
Oesophagostomum
