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43 Cards in this Set

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What causes Parasitic Gastroenteritis in cattle?
Abomasum: Ostertagia ostertagi (PRIMARY)
Small Intestine: Cooperia spp, Nematodirus spp
Ostertagiosis Type 1 (in cattle)
Straightforward disease due to L3 ingested 3-4 weeks earlier. Usually during first grazing season in calves.
Usually mid July to October.
High morbidity/low mortality
Causes diarrhea, wt loss, reduced appetite.
Ostertagiosis Type 2 (in cattle)
Accumulation of large population (>100,000) of EL4 Ostertagia (arrested stage) that have overwintered.
Due to L3 ingested in late Autumn.
Initially no clinical signs (Pre-Type 2 stage).
Disease occurs when development resumes: waves of EL4 become active.
Low morbidity/high mortality.
Diarrhea (waves), wt loss, reduced appetite, submandibular edema.
What is the life cycle of Ostertagia ostertagi?
Life cycle > infective L3 ingested from environment > development to L4 and adult stages is generally restricted to gastric or intestinal mucosa (a few migrate) > adults emerge to lie on mucosal surface, prepatent period normally 3 weeks though may be 6+ months for certain species or if development is “arrested”.
How does the rate of infection of Ostertagia ostertagi in cattle occur?
Infective larvae overwinter on pasture. Larval numbers decline in spring. New infections develop when stock is turned out to pasture and ingest overwintered L3 larvae. Eggs then pass out on pasture. Egg develops to L3. L3 make their way to blades of grass. Infection peaks in cattle from Concertina effect and high numbers of L3 on pasture ingested.
What is the cause of Parasitic Bronchitis in cattle?
Dictyocaulaus viviparus
aka Bovine Lungworm
or the lungworm of ruminants
Name the species:
Parasite of cattle
Filarial nematode
Indirect life cycle
Intermediate host: black fly Similium spp and biting midge, Culicoides spp
Subcutaneous and intramuscular nodules cause economic loss (ie big problem in Australia)
Onchocerca spp.
Name the species:
Parasite of cattle
Bovine “eyeworm”
A spiruroid nematode
Hooked shaped tail (males)
Conjunctival sac, inner aspect third eyelid, lachrymal duct
Lacrymation and conjunctivitis in heavy infections
Indirect life cycle: Musca spp (nuisance flies)
Thelazia spp.
What are the primary pathogens of sheep?
Abomasum:
Ostertagia circumcincta
Haemonchus contortus

Small Intestine:
Trichostrongylus spp.
Nematodirus battus
Ostertagiosis Type 1 (in sheep)
Predominant form of Parasitic Gastroenteritis in sheep.
Affects lambs at first grazing season (July – September).
Diarrhea, wt loss, reduced appetite.
Ostertagiosis Type 2 (in sheep)
Affects lambs over 1 year old after first grazing season.
Progressive wt loss, intermittent diarrhea.
What occurs during periparturient relaxation in immunity (sheep)?
Increased establishment of L3.
increased egg production per female worm.
Resumed development of arrested larvae> HIGH fecal egg count around lambing time.
Name the species:
Affects lambs 6-10 weeks old at beginning of first grazing season.
Small intestine.
Causes profuse diarrhea, rapid dehydration and death.
Large strongyle egg.
Parasite has cotton wool appearance.
Nematodirus
Name the species:
Affects sheep.
Predilection site is abomasum.
Can cause severe anemia.
Piercing lancet/blood-sucking.
Likes tropics/warm weather.
High biotic potential-eggs can survive long dry periods, but eggs do not overwinter well.
Disease epidemiology is similar to Type 2 Ostertagiosis.
Haemonchus contortus
Name the species:
A lungworm of sheep and goats.
Causes chronic cough and unthriftiness.
Usually just affects lambs and kids.
Direct life cycle.
Prepatent period is 5 weeks.
Dictyocaulus filaria
Name the 2 similar species:
Lungworms of sheep and goats.
Indirect life cycle.
Mollusk is intermediate host.
L1 from feces >penetrates foot of mollusc > develop to L3 in 2-3 weeks > mollusc ingested with grass > travel to lungs via lymphatics route > adults in alveoli.
Muellerius spp.
Protostrongylus spp.
What are the primary pathogens of horses?
LARGE STRONGYLES:
Strongylus spp
Triodontphorus
SMALL STRONGYLES:
Cyathostomes
Name the species:
Equine roundworms.
Ascarid.
Occurs mostly in foals <6 months old.
Direct life cycle.
Hepatotracheal migration.
Larvae migrates through lungs.
Causes cough and nasal discharge.
Foals pass millions of eggs a day and saturate the environment.
Foals transmit from one year to the next.
Parascaris equorum
Name the species:
Equine threadworms.
Rhabditoid.
Females are parasitic.
The first parasite to which foals are exposed.
Foals can become infected through mother's milk.
Hepatotracheal migration.
Adult horses usually immune.
Strongyloides westeri
Name the species:
Equine pinworms.
Only larvae are pathogenic.
Females migrate to anus >lay eggs on perianal hair > eggs fall to ground >L3 develops in egg>egg ingested>L3 invades colonic mucosa>develops to L4>matures to adult.
L4 feed on colon mucosa, causing lesions.
Oxyuris equi
Name the species:
Horse lungworm.
Causes chronic cough.
Donkeys are major source of infection.
Donkeys shed eggs, horses rarely do.
Donkeys rarely exhibit clinical signs.
Dictyocaulus arnfieldi
What are the primary pathogens of Parasitic Gastroenteritis in pigs?
Hystrongylus rubidus (stomach)
Ascaris suum (small intestine)
Oesophagostomum spp (large intestine)
Strongyloides ransomi (large intestine) – younger litters
Trichuris suis (large intestine)
What is the kidney worm of pigs?
Stephanurus dentatus
What is the scientific name of the "barber pole" worm?
Haemonchus contortus
Which nematode is usually asymptomatic in pigs, but potentially zoonotic?
Trichinella spiralis
Name the species:
Affects pigs.
Predilection site is glandular part of stomach.
Life cycle, epidemiology, and pathogenicity is similar to Ostertagia.
Pigs never develop immunity.
Seen only in outdoor pigs.
Typical stongyloid.
Causes severe weight loss and even death in lactating sows.
Hystrongylus rubidus
Name the species:
Very common parasite of pigs.
Sometimes no clinical effects are seen.
Not very pathogenic, but large numbers depress milk production in sows and growth rate in young pigs.
Typical strongyloid.
Predilection site is cecum and colon.
Oesophagostomum spp.
Name the species:
Affects pigs.
Long, ascarid worm.
Egg is thick and sticky, making disinfection of buildings difficult.
Hepatotracheal migration.
Causes liver damage- "milk spot"
Large numbers can also cause lung pathology, respiratory distress, pneumonia.
Ascaris suum
Thin Sow Syndrome
A nutritional problem usually associated with downturns in the pig industry.
Occurs gradually over several months.
Pigs are fed less, and become more likely to eat bedding, which can contain infective L3 larvae.
Pigs end up aquiring a large worm burden, which causes intestinal damage, and even more eggs to be excreted into the environment.
This creates a downward spiral.
Name the species:
Affects mostly outdoor pigs.
Typical whipworm.
Prefers warmer climates.
Can cause severe diarrhea or dysentery.
Provides a portal entry for microbial organisms.
Trichuris suis
Name the species:
Females lay pre-larvae, not eggs.
Infections in pigs is usually asymptomatic.
Infections in humans is serious, potentially fatal.
Forms cysts in prey animal, predator becomes infected by eating prey.
Adult and larval stages occur in same animal.
Pig can act as both predator and prey.
Found in small intestine of pigs, humans, and other carnivores.
Trichinella spiralis
Name the species:
Lungworm of pigs.
3 species, all similar
Only outdoor pigs get it.
Very pathogenic.
Earthworm is intermediate host.
Metastrongylus spp.
Name the species:
Affects outdoor pigs.
Strongyloidea.
Adult worms in and around peri-renal fat and ureters.
Eggs passed in urine.
Earthworm is transport host.
Migrates from liver>peritoneal cavity>kidney.
Causes poor growth and condemnation of carcass at slaughter.
Stephanurus dentatus
Name the species:
Affects pigs.
Transmitted in sow's milk.
Very pathogenic in young litters.
Strongyloides ransomi
What are the 3 disease syndromes that Toxocara canis can cause in humans?
Visceral Larval Migrans (VLM)-symptoms include eosinophilia, hepatomegaly, fever, asthma.
Ocular Larval Migrans- unilateral partial impairment of vision.
Covert Toxocarosis(iasis)- non-specific clinical signs associated with high Ab titre.

Most cases of human infection with Toxocara canis are not serious, and the person may not even notice any symptoms. Infections are likely to be more serious in young children.
What is the life cycle of Toxocara canis?
Larvae migrate via hepatotracheal route > small intestine > become adult > eggs passed in feces
PPP is about 4-5 weeks
What are the hookworms of dogs and where is their predilection site?
Ancylostoma caninum
Uncinaria stenocephala

In the small intestine.
What is the whipworm of dogs and where is it's predilection site?
Trichuris vulpis
In the cecum.
What is the predilection site for both Toxocara canis and Toxascaris leonina?
The small intestine.
What is the lungworm of dogs?
Filaroides osleri
What are the 2 heartworms of dogs?
Dirofilaria immitus
Angiostrongylus vasorum
What is the lungworm of cats?
Aelurostrongylus abstrusus
How can a dog become infected with Toxocara canis?
Prenatal
Transmammary
Ingestion of a paratenic host