Histomonas meleagridis 

Intro to Histomonas meleagridis 

1. WELLCOME 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 μ m in diameter) . In caecum, it lives as an elongated  flagellate  form (8–15 μ m 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. I t 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 S ulfur-colored droppings

6. Postmortem Primary lesions as caecal ulceration ( 3–4 days after invasion). N ecrotic 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 E xamination 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.