Sarcosporidian cysts in the skeletal muscle of domestic pigeons (Columba livia f. domestica) have previously been attributed to infection with Sarcocystis falcatula, which is shed in the faeces of the opossum (Didelphis virginiana). Here, we describe fatal spontaneous encephalitis and myositis associated with Sarcocystis infections in three flocks of racing pigeons with 47 of 244 animals affected. The clinical course was characterized by depression, mild diarrhoea, torticollis, opisthotonus, paralysis and trembling. Histopathological examination of 13 pigeons revealed generalized severe granulomatous and necrotizing meningoencephalitis and myositis with sarcosporidian cysts. Light and transmission electron microscopy identified cysts in heart and skeletal muscle of 1 to 2 mm in length and 20 to 50 m in width. These were subdivided into small chambers by fine septae and filled with lancet-shaped cystozoites (7.51.5 m) and dividing metrocytes, which is characteristic for Sarcocystis. The cysts had smooth walls and were devoid of protrusions typical of S. falcatula. Polymerase chain reaction amplification and sequencing of the internal transcribed spacer region (ITS-1) and the complete 28S rRNA identified a novel Sarcocystis species with only 51% ITS-1 nucleotide sequence similarity with S. falcatula. A phylogenetic comparison of the 28S rRNA revealed close sequence homologies with Frenkelia microti, Frenkelia glareoli and Sarcocystis neurona. The clinical, histopathological, electron microscopic and genetic data are unlike any previously described protozoan infections in pigeons, suggesting a novel, severe disease due to an as yet undescribed Sarcocystis species.
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Univ Georgia, Coll Vet Med, SE Cooperat Wildlife Dis Study, Athens, GA 30602 USAUniv Georgia, Coll Vet Med, SE Cooperat Wildlife Dis Study, Athens, GA 30602 USA
Teglas, MB
Little, SE
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机构:Univ Georgia, Coll Vet Med, SE Cooperat Wildlife Dis Study, Athens, GA 30602 USA
Little, SE
Latimer, KS
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机构:Univ Georgia, Coll Vet Med, SE Cooperat Wildlife Dis Study, Athens, GA 30602 USA
Latimer, KS
Dubey, JP
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机构:Univ Georgia, Coll Vet Med, SE Cooperat Wildlife Dis Study, Athens, GA 30602 USA
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Univ Edinburgh, Royal Dick Sch Vet Studies, Easter Bush EH25 9RG, Midlothian, Scotland
Univ Edinburgh, Roslin Inst, Easter Bush EH25 9RG, Midlothian, ScotlandUniv Edinburgh, Royal Dick Sch Vet Studies, Easter Bush EH25 9RG, Midlothian, Scotland