JPC SYSTEMIC PATHOLOGY
Signalment (JPC # 1644924): Golden pheasant (Chrysolophus pictus)
HISTORY: This pheasant was found dead in a zoo.
HISTOPATHOLOGIC DESCRIPTION: Cecum: Multifocally expanding the submucosa and elevating the overlying mucosa, are multiple, focal to coalescing nodules up to 2 mm in diameter, composed of spindle cells arranged in whorls and interlacing bundles, admixed with macrophages, multinucleated giant cells, lymphocytes, and plasma cells, often centered on adult or larval nematodes. Adult nematodes are up to 500 um in diameter and have a thin smooth cuticle, lateral alae, polymyarian/coelomyarian musculature, lateral cords, a pseudocoelom, an intestinal tract lined by columnar uninucleate cells with a brush border, an ovary, and a uterus containing developing ova. Nodules often contain one or more variably sized granulomas with a central core of necrotic debris surrounded by a thin rim of epithelioid hemosiderin laden macrophages, multinucleated giant cells, and fewer fibroblasts, lymphocytes and plasma cells. Diffusely the lamina propria is expanded by moderate numbers of lymphocytes, plasma cells, and fewer hemosiderin laden macrophages, often in aggregates, heterophils, and increased clear space (edema). The crypts are multifocally shallow and widely separated by the edematous lamina propria, and the superficial mucosa is multifocally eroded. Numerous small coccobacilli multifocally line the luminal epithelium.
MORPHOLOGIC DIAGNOSIS: Cecum: Typhlitis, granulomatous, multifocal, moderate, with atypical nodular mesenchymal proliferations, and adult and larval nematodes, etiology consistent with Heterakis isolonche, golden pheasant (Chrysolophus pictus), avian
ETIOLOGIC DIAGNOSIS: Cecal heterakiasis
CAUSE: Heterakis isolonche
- Order Ascarida, suborder Heterakina; primarily found in the cecum of birds
- Most heterakids are non-pathogenic, with the exception of Heterakis isolonche
- isolonche most common in the pheasant; also reported in ducks, grouse, pheasants, prairie chickens and quail
- Herterakiasis often called “verrucous typhlitis” due to the appearance of the cecal wall
- Recent report of large intestinal isolonche infection in a pheasant; nodular typhlocolitis progressed to neurofibromatous malignant mesenchymal neoplasia with pulmonary and hepatic metastases
- Direct: Unembryonated eggs passed in feces > embryonate to reach infective stage in the environment in 12-14 days > bird ingests infective eggs directly or via transport host (annelid worm) > eggs hatch in crop, gizzard or duodenum > larvae migrate to cecum and penetrate mucosa > adults develop with nodules > return to the cecal lumen to complete development
TYPICAL CLINICAL FINDINGS:
- May be asymptomatic
- Diarrhea and emaciation; high mortality with heavy infections
TYPICAL GROSS FINDINGS:
- Cecal wall thickened by multiple 1-2 mm, raised mucosal nodules (cobblestone appearance) that are white-gray, light pink or dark brown; worms occasionally visible within nodules
TYPICAL LIGHT MICROSCOPIC FINDINGS:
- Nodules of proliferating fibrous tissue induced by larvae:
- The nature of this reaction is controversial; it has been considered granulomatous, fibroplastic or neoplastic
- Nodules of spindle cells arranged in whorls and interlacing bundles have been described as “sarcomatous” or “pseudoneoplastic”
- This nodular proliferation is not seen in quail and grouse
- Lymphoplasmacytic to granulomatous typhlitis
- Granulomas form in response to dead parasites
- Parasite morphology:
- Thin smooth cuticle, cuticular alae, lateral cords, a pseudocoelom
- Polymyarian/coelomyarian musculature
- Intestinal tract: Cuboidal to columnar uninucleate cells with a brush border
- Ovary and a uterus containing developing eggs
- Differentiated from Heterakis gallinarum by size and appearance of spicules
ADDITIONAL DIAGNOSTIC TESTS:
- Fecal flotation may reveal heterakid eggs
- Heterakis beramporia: Similar lesion in chickens in Asia and the Pacific area
- gallinarum: No significant pathology, but carries Histomonas meleagridis, the etiologic agent of blackhead in gallinaceous birds; ring-necked pheasant is ideal host, followed by guinea fowl and chickens
- Heterakis bonasae: Infect ceca of ruffled grouse and Bobwhite quail; prevalence and worm burdens can be high
- Heterakis dispar: Infect ceca of ducks and geese but are relatively non-pathogenic
- Rodents: Heterakis spumosa
- Abdul-Aziz T, Barnes HJ. Avian Histopathology Text and Atlas. Jacksonville, FL: American Association of Avian Pathologists; 2018: 181.
- Gardiner CH, Poynton SL. An Atlas of Metazoan Parasites in Animal Tissue. Washington DC: Armed Forces Institute of Pathology; 1999: 20.
- Griner LA, Migaki G, Penner IR, McKee AE. Heterakidosis and nodular granulomas caused by Heterakis isolonche in the ceca of gallinaceous birds. Vet Pathol. 1977; 14: 582-590
- Himmel L, Cianciolo R. Nodular typhlocolitis, heterakiasis, and mesenchymal neoplasia in anring-necked pheasant (Phasianus colchicus) with immunohistochemical characterization of visceral metastases. J Vet Diag Invest. 2018; 29(4): 561-565.
- Menezes RC, Tortelly R, Gomes DC, Pinto RM. Nodular typhlitis associated with the nematodes Heterakis gallinarum and Heterakis isolonche in pheasants: Frequency and pathology with evidence of neoplasia. Mem Inst Oswaldo Cruz. 2003; 98: 1011-1016.
- McDougald LR. Internal parasites. In: Swayne DE, ed. Diseases of Poultry. 13th ed. Ames, IA: John Wiley & Sons, Inc.; 2013: 1123-1124.