May 2019

SIGNLAMENT (JPC # 2741020):  Chilean flamingo

HISTORY:  This animal was weak and ataxic.  Sections of the heart were positive via immunohistochemistry and in situ hybridization for West Nile virus.

HISTOPATHOLOGIC DESCRIPTION:  Heart:  Multifocally affecting approximately 50% of the myocardium, separating and surrounding cardiomyocytes and Purkinje fibers, and multifocally infiltrating the epicardium, are numerous lymphocytes, plasma cells and macrophages.  Adjacent cardiomyoctes are often shrunken, hypereosinophilic, or fragmented with loss of cross striations, have pyknotic or karyolytic nuclei, and are surrounded by eosinophilic cellular and karyorrhectic debris (necrosis).  Rare cardiomyocytes are pale, swollen and vacuolated (degenerate). Frequently, similar inflammatory cells infiltrate the epicardium. Previously mentioned inflammatory cells extend into adjacent epicardial adipose tissue, which is diffusely composed of shrunken and variably sized adipocytes (fat atrophy).


  1. Heart:  Pancarditis, necrotizing, lymphoplasmacytic and histiocytic, multifocal to coalescing, moderate, subacute, Chilean flamingo (Phoenicopterus chilensis), avian.
  2. Heart, epicardium: Fat atrophy, diffuse, moderate. 

ETIOLOGIC DIAGNOSIS:  Flaviviral myocarditis

CAUSE:  West Nile virus












  1. Bowen R, Greene C, Rickettsial, chlamydial and mycoplasmal diseases. In: Greene CE, ed. Infectious Diseases of the Dog and Cat. 4th ed. St. Louis, MO: Saunders Elsevier; 2012:214-217.
  2. Eckstrand CD,et al. Diagnostic exercise: High mortality in a flock of chukar partridge chicks (Alectoris chukar) in California. Vet Pathol. 2015 ;52(1):189-92.
  3. Fulton RM, Boulianne M. Bacterial diseases. In: Boulianne M, ed.  Avian Disease Manual. 7th ed. Jacksonville, FL: American Association of Avian Pathologists, Inc; 2013:16-24.
  4. Gamino V, Escribano-Romero E, Blázquez AB, Gutiérrez-Guzmán AV, Martín-Acebes MÁ, Saiz JC, Höfle U. Experimental north american west nile virus infection in the red-legged partridge (Alectoris rufa). Vet Pathol. 2016 May;53(3):585-593
  5. Gamino V, Escribano-Romero E, Gutiérrez-Guzmán AV, Blázquez AB, Saiz JC, Höfle U. Oculopathologic findings in flavivirus-infected gallinaceous birds. Vet Pathol. 2014 Nov;51(6):1113-1116.
  6. Grant Maxie M, Youssef S. Nervous system. In: Grant Maxie M, ed. Jubb, Kennedy, and Palmer’s Pathology of Domestic Animals. Vol 1. 6th ed. Philadelphia, PA: Elsevier; 2016:374-375.
  7. Hofmeister EK, Lund M, Shearn Bochsler V. West Nile Virus Infection in American Singer Canaries: An Experimental Model in a Highly Susceptible Avian Species. Vet Pathol. 2018 Jul;55(4):531-538.
  8. MacLachlan NJ, Dubovi EJ. Fenner’s Veterinary Virology. 4th ed. London, UK: Academic Press; 2017: 533-535.
  9. Nemeth NM, Bosco-Lauth AM, Williams LM, Bowen RA, Brown JD. West Nile Virus Infection in Ruffed Grouse ( Bonasa umbellus): Experimental infection and protective effects of vaccination. Vet Pathol. 2017 Nov;54(6):901-911.
  10. Nemeth NM, Thomsen BV, Spraker TR, et al. Clinical and pathologic responses of american crows (Corvus brachyrhynchos) and fish crows (C ossifragus) to experimental West Nile virus infection. Vet Pathol. 2011; 48(6):1061-1074.
  11. Palmieri C, Franca M, Uzal F, et al. Pathology and immunohistochemical findings of West Nile virus infection in psittaciformes. Vet Pathol. 2011; 48(5):975-984.
  12. Porter MB, Long MT, Getman LM, Giguere S, et al. West Nile virus encephalomyelitis in horses: 46 cases (2001). J Am Vet Med Assoc. 2003; 222(9):1241-1247.
  13. Rimoldi G, Mete A, Adaska JM, Anderson ML, Symmes KP, Diab S. West nile virus infection in sheep. Vet Pathol. 2017 Jan;54(1):155-158.
  14. Schmidt RE, Reavill DR, Phalen DN. In: Schmidt RE, Reavill DR, Phalen DN. eds. Pathology of Pet and Aviary Birds, Second Edition. Iowa State Press. Ames, Iowa. 2015: 224-225.
  15. Toplu N, Oquzoglu T, et al. West Nile virus infection in horses: Detection by immunohistochemistry, in-situ hybridization, and ELISA. Vet Pathol. 2015; 52(6):1073-1076.
  16. Williams J, Mentoor J, et al. Comparative pathology of neurovirulent lineage 1 (NY99/385) and lineage 2 (SPU93/01) West Nile virus infections in BALBc mice. Vet Pathol. 2015; 52(1): 140-151.
  17. Wünschmann A, Armién AG, Khatri M, Martinez LC, Willette M, Glaser A, Alvarez J, Redig P. Ocular lesions in red-tailed hawks (Buteo jamaicensis) with naturally acquired west nile disease. Vet Pathol. 2017 Mar;54(2):277-287.
  18. Wünschmann A, Timurkaan N, Armien AG, Bueno Padilla I, Glaser A, Redig PT. Clinical, pathological, and immunohistochemical findings in bald eagles (Haliaeetus leucocephalus) and golden eagles (Aquila chrysaetos) naturally infected with West Nile virus. J Vet Diagn Invest. 2014 Sep;26(5):599-609.

Click the slide to view.

Click on image for diagnostic series.

Back | Home | Contact Us | Links | Help |