Histomonas spp. (1) Flashcards
What are the hosts?
Fowl
- Primarily turkey
Heterakis = vector
What is the common name?
Blackhead
How do you identify?
Round/oval
6-20 micro m in diameter
Single flagellum
- Lost in mucosal tissue of liver
Luminal and tissue stages exhibit pseudopodial movement
Explain the life cycle
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
What are the sites of infection?
Cecum - flagellated
Liver - nonflagellated
Describe the Pathogenesis
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
How do you diagnose?
History
Clinical signs
Lesions or identification of Trophozoites in liver/cecum
How do you treat and prevent?
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