Histomonas spp. (1) Flashcards

1
Q

What are the hosts?

A

Fowl
- Primarily turkey

Heterakis = vector

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2
Q

What is the common name?

A

Blackhead

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3
Q

How do you identify?

A

Round/oval

6-20 micro m in diameter

Single flagellum
- Lost in mucosal tissue of liver

Luminal and tissue stages exhibit pseudopodial movement

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4
Q

Explain the life cycle

A

Free Trophozoites pass in feces - die
- No role in transmission

Birds can ingest egg with trophozoites

Trophozoites in eggs of Heterakis gallinarum (passed in feces) readily infective to other birds

Remain viable in heterakoid eggs for months

Eggs often ingested by earthworms

Birds ingest earthworm
- Infected by both nematode and flagellate

Trophozoites released from egg

Invade cecal wall

Protozoan loses its flagellum - becomes pleomorphic and Amoeboid

Migrates to liver

Infect cecum and liver

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5
Q

What are the sites of infection?

A

Cecum - flagellated

Liver - nonflagellated

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6
Q

Describe the Pathogenesis

A

Disease known as infectious enterohepatitis
- Affects young turkeys - can be fatal
- Hemorrhagic liver with characteristic lesions
- Yellow/Yellow-green circular depressions of tissue that is
degenerate and necrotic
- Marked cecal inflammation/ulcerations

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7
Q

How do you diagnose?

A

History

Clinical signs

Lesions or identification of Trophozoites in liver/cecum

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8
Q

How do you treat and prevent?

A

Dimetridazole effective

Good management

Hygiene

Turkeys should be reared on ground that has not been used to rear birds (domestic chickens) for at least 2 years

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