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Histomonas meleagridis
- 2. Introduction • First report in Rhode Island (USA) in 1893 in Turkeys. • Histomonas meleagridis is an anaerobic protozoan parasite. • It is an anaerobic , pleomorphic protozoan, and can exist in two forms, amoeboid and flagellated. • Within the tissue, it is present as an amoeboid form (8–30 μm in diameter) . • In caecum, it lives as an elongated flagellate form (8–15 μm in diameter).
- 3. Cont. • It causes infectious enterohepatitis, or histomoniasis (blackhead diseases). • It infects a wide range of gallinaceous birds including chicken, turkeys, pheasants, peafowls and quails. • It is most deadly in turkeys (80%-100%). • Chickens are typically asymptomatic carriers.
- 4. Transmission • It is transmitted by another caecal parasite, the nematode Heterekis gallinarum. • Earthworm can act as Paratenic host. • In turkeys, transmission by direct cloacal contact with infected birds
- 5. Clinical Sign & Symptoms • Signs of histomoniasis are apparent in turkeys 7–12 days after infection and include: • Prolonged standing • Closed eyes • Emaciation • Drooping head and wings • Ruffled feathers • Sulfur-colored droppings
- 6. Postmortem • Primary lesions as caecal ulceration (3–4 days after invasion). • Necrotic lesions in the liver (6–8 days after infection) • Lesions are also seen in other organs, such as kidneys, spleen, and pancreas.
- 7. Diagnosis • Clinical signs. • The liver and caecal lesions are pathognomonic • Examination of cecal/liver contents under a microscope • PCR • Histopathologic examination
- 8. Treatment & Prevention • There are no approved treatments or vaccines. • Turkeys should not be raised with other galliformes such as chickens. • Control earthworm.