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VM638: Parasitology > Sheep & Goats (Exam 2) > Flashcards

Sheep & Goats (Exam 2) Flashcards

1
Q

What is the taxonomy of fasciola hepatica?

A

Common liver fluke
Platyhelminth - Trematode
Monoecious
Digenean

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2
Q

What is the geographic distribution of fasciola hepatica?

A

Worldwide
Moist/humid regions

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3
Q

Where is fasciola hepatica located in the host?

A

Liver/bile ducts

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4
Q

What are the hosts for fasciola hepatica?

A

Herbivores
Cattle, sheep, goats, ruminants, horses, pigs

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5
Q

What diagnostics are used for fasciola hepatica?

A

“Fluke finder” for finding eggs in stool sample
Sedimentation is diagnostic of choice!
Liver enzyme tests

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6
Q

What is the morphology of fasciola hepatica?

A

Eggs are golden brown, operculate
Leaf-like
Cephalic cone: anterior end cone-shaped
Distinct “shoulders”
Ventral acetabulum close to oral sucker
Testes, uterus dendritic and vitelline cells extensive
Covered with spines as adults

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7
Q

What is the life cycle of fasciola hepatica?

A

Miracidium penetrates a snail host and immature stages develop –> sporocyst, rediae, cercariae –> motile cercariae leave the snail and encyst on grass to form infective metacercariae –> ingestion –> encyst in sm. intestine, migrate through wall (immature flukes migrate through liver parenchyma) –> eggs leave liver through bile ducts –> passed in stool –> unembryonated eggs deposit into water –> ciliated miracidia hatch and live to find snail

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8
Q

Where do adults/immature fasciola hepatica live?

A

Immature: liver parenchyma
Adults: bile ducts

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9
Q

What is the intermediate host in the fasciola hepatica lifecycle?

A

Indirect!
Lymnae spp. snails
Important in expansion of introduced transmission to new areas

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10
Q

What is the importance of fasciola hepatica infections?

A

Economic importance due to loss of milk/meat production, condemnation of livers, expensive anthelmintic treatments, secondary bacterial infections, animal mortality

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11
Q

What are the acute/subacute pathogenesis/clinical signs of fasciola hepatica infection?

A

Migration of immature flukes cause hemorrhage and inflammation
Abdominal pain
Hepatomegaly
Fever, weight loss, inappetence
Anemia
Sudden death
Typically sheep and goats

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12
Q

What are the chronic pathogenesis/clinical signs of fasciola hepatica infection?

A

Caused by adult flukes
Symptoms may be intermittent
+/- secondary bacterial infections
Biliary obstruction, inflammation, fibrotic changes
Submandibular edema, emaciation, ascites
Typically in cattle

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13
Q

What are chronic signs of fasciola hepatica in cattle?

A

Gradual weight loss
Poor feed conversion
Constipation
+/- anemia in calves

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14
Q

What are acute signs of fasciola hepatica in sheep?

A

Bloody nasal discharge
Bloody anal discharge
Weakness
Anemia
Sudden death

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15
Q

What is the pathogenesis of fasciola hepatica?

A

Immature flukes destroy liver parenchyma, hemorrhagic tracts; hemorrhage into peritoneal cavity
Collagen laid down as liver regenerates; fibrosis of liver parenchyma
Hyperplastic cholangitis from severe necrosis of biliary mucosa
Calcification of bile ducts
Black’s disease (secondary bacterial infection)
Aberrant migration to lungs (cattle)

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16
Q

How is fasciola hepatica treated?

A

Praziquantel, albendazole

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17
Q

How is fasciola hepatica prevented?

A

Avoid eating vegetation containing mtacercaria
Molluscides can be used to kill snails
Pasture rotation (reservoir hosts maintain pasture contamination)

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18
Q

Is fasciola hepatica zoonotic?

A

Yes
Especially in places where cattle are raised
Human infections rare in the US

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19
Q

What is the taxonomy of moniezia spp.?

A

Cestoda
Tapeworm

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20
Q

What is the geographic distribution of moniezia spp.?

A

worldwide

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21
Q

What is the location of moniezia spp. in the host?

A

GI tract
Small intestine

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22
Q

What are the hosts of moniezia spp.?

A

Hooved animals
Cattle, other ruminants, camelids

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23
Q

What is the morphology of moniezia spp. adults?

A

Large tapeworms
Proglottids are more wide than long
Two sets of reproductive organs in each proglottid
Scolex is “unarmed”

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24
Q

What is the morphology of moniezia spp. eggs?

A

Monezia benedeni: square
Monezia expansa: triangular
Eggs possess a pyriform apparatus, and an embryophore with hook- or horn-like extensions
Metacestode stage (larval tapeworm): “cystercoid”

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25
Q

What is the life cycle of moniezia spp.?

A

Eggs ingested by mites –> sheep eat infested mite –> worm matures in small intestine –> eggs shed in feces

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26
Q

What are the clinical signs of moniezia spp. infection?

A

Relatively benign, may show no clinical signs
Low significance in healthy adult animals, but may be important in young animals: digestive disorders, diarrhea, cachexia

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27
Q

What is the taxonomy of muellerius capillaris?

A

Nematode
Nodular lungworms

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28
Q

What is the geographic distribution of muellerius capillaris?

A

worldwide except for arctic and subarctic

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29
Q

What is the location of muellerius capillaris in host?

A

Lungs

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30
Q

What is one of the most common genera of sheep lungworms?

A

muellerius capillaris

31
Q

What is the morphology of muellerius capillaris?

A

Larval tail has an undulating tip and dorsal spine
Adults are difficult to discern when embedded in lung tissue

32
Q

What is the diagnostic of choice for muellerius capillaris?

A

L1 detected with Baermann

33
Q

What is seen at necropsy with muellerius capillaris infections?

A

Pulmonary lesions and evidence of nematode infection on histology

34
Q

What is the life cycle of muellerius capillaris?

A

Intermediate hosts: snails, slugs
L1 larvae coughed up and swallowed
Ruminant ingests intermediate host with L3
Migrate to heart, lungs, alveoli, and bronchioles to mature via circulatory system

35
Q

What are the clinical signs associated with muellerius capillaris infection?

A

Infection may be inapparent
Worms may be associated with inflammation
Nodules or granuloma-like lesions may form on lung surface with adults, eggs, and L1 larvae
Dyspnea, coughing, or other respiratory signs, secondary bacterial infections possible

36
Q

Is muellerius capillaris zoonotic?

A

No

37
Q

What is the taxonomy of strongyloides spp.?

A

Nematode

38
Q

What is the geographic distribution of strongyloides spp.?

A

worldwide
Especially tropical regions

39
Q

What is the location of strongyloides spp. in host?

A

GI tract

40
Q

What are the hosts of strongyloides spp.?

A

Ruminants!
multiple other hosts

41
Q

What is the morphology of strongyloides spp.?

A

Slender, hair-like worms
Esophagus of adult parasitic worm is 1/3 of the body length
Eggs small, thin shelled, brick-shaped

42
Q

What form of strongyloides spp. is passed by herbivores? Other animals?

A

Herbivores: larvated eggs
Other animals: larvae

43
Q

What are the larvae forms/names of strongyloides spp.?

A

L1 = rhabditiform
L3 = filariform

44
Q

What are the diagnostics of choice for strongyloides spp.?

A

Finding larvae or eggs in the stool
Larvated eggs!!
Creates confusion because eggs can become larvated when sitting on pasture over time

45
Q

What are the 2 cycles of strongyloides spp.?

A

Homogonic: host-associated phase
Heterogonic: free-living phase

46
Q

Describe the homogonic life cycle of strongyloides spp.

A

Free-living phase
Rhabditiform larvae molt multiple times into male and female adults; temperature determines type of life cycle
Larvae can remain free-living for successive generations or molt to infective L3

47
Q

What is the primary route of infection of strongyloides spp. in sheep vs cattle?

A

Sheep: percutaneous
Cattle: transmammary

48
Q

What are the clinical signs associated with strongyloides spp. infection?

A

Infection in older animals often inapparent
May be asymptomatic in young animals as well
Following percutaneous infection: erosion of intestinal mucosa, anorexia, decreased weight gain, diarrhea, foot rot (due to bacterial infection)

49
Q

Is strongyloides spp. zoontoic?

A

Yes
May cause cutaneous larval migrans in humans

50
Q

What is the taxonomy of oestrus ovis?

A

Oestridae
Obligatory fly species
The sheep nasal bot

51
Q

What is the geographic distribution of oestrus ovis?

A

All sheep farming regions of the world

52
Q

Where is oestrus ovis located in the host?

A

Nasal cavities

53
Q

What is the morphology of oestrus ovis?

A

Mature larvae in the nasal passages are yellow-white in color and taper anteriorly
Large, black, oral spines
Spiracles: respiratory tubes of arthropods at posterior end

54
Q

What is the life cycle of oestrus ovis?

A

Females are viviparous
Squirt a jet of liquid into nostrils during flight (containing ~25 larvae)
L1 migrate to frontal sinuses feeding on mucus
Attach via oral hooks which cause irritiation
Eventual molt to L3 occurs in frontal sinuses, then migrate back to nostrils

55
Q

What are the environmental factors of oestrus ovis?

A

Most infections light
Can overwinter in recesses of nasal passages, depending on climate

56
Q

What are the clinical signs of oestrus ovis?

A

Nasal discharge
Sneezing
Irritation
Unthriftiness, circling (if severe)
+/- secondary bacterial infections

57
Q

How is oestrus ovis controlled/treated/prevented?

A

When adult flies approach, animals panic, stamp feet, and cluster together
May not be economically viable to treat, but macrocyclic lactones (endectocides) are common treatments among others

58
Q

Is oestrus ovis zoonotic?

A

Can occasionally infect humans
Catarrhal conjunctivitis or stomatitis, but no development

59
Q

What is the taxonomy of melophagus ovinus?

A

Insecta (Flies, Hippoboscidae)
The Sheep Ked

60
Q

What is the geographic distribution of melophagus ovinus?

A

Worldwide, common in temperate areas

61
Q

Where is melophagus ovinus located in the host?

A

Ectoparasite of sheep
Wool-associated

62
Q

What is the morphology of melophagus ovinus?

A

Hairy, brown, wingless fly
6-legged adults
Piercing, sucking mouthparts, strong legs and claws

63
Q

What is the life cycle of melophagus ovinus?

A

Permanent ectoparasites
Live for several months feeding on blood of sheep and goats
Ked populations build slowly with 10-20 larvae produced by a female in her lifetime

64
Q

What are the transmission dynamics of melophagus ovinus?

A

Heaviest infestations in fall and winter
Transfer common when keds are at tip of fleece due to temperature
Animals in poor condition are most likely to suffer

65
Q

What are the clinical signs of melophagus ovinus infection?

A

Heavy infestations lead to anemia
Inflammation
Pruritis, biting, rubbing, wool loss
Allergic dermatitis

66
Q

How is melophagus ovinus treated/controlled/prevented?

A

Shearing removes pupae and adults
Routine insecticides usually helpful
Considerable economic importance

67
Q

What is one of the most damaging ectoparasites of sheep in the US?

A

melophagus ovinus

68
Q

What is the taxonomy of psosoptes spp.?

A

Mites

69
Q

What is the geographic distribution of psosoptes spp.?

A

worldwide

70
Q

Where is psosoptes spp. located in the host?

A

Ears

71
Q

What is the morphology of psosoptes spp.?

A

Caruncles, pedastles, stocks
Long stock, jointed

72
Q

How is psosoptes spp. transmitted?

A

Direct transmission between hosts

73
Q

What are the clinical signs associated with psosoptes spp.?

A

Lesions on the ventrum of a sheep
Psoroptic mange in ruminants
Crusted lesions in a goat: lesions consist of exudative dermatitis and hair loss, often beginning in the ear and spreading to the head and neck
Mites live superficially on the skin surface and are easily collected with a superficial skin scraping or scabs that have been broken apart

VM638: Parasitology (22 decks)

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