Western
Meeting of Poultry
Clinicians and Pathologists
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Clinicians and Pathologists
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Meningeal Vasculitis and Encephalitis Associated with Mycoplasmosis in Turkeys R.P. Chin California Veterinary Diagnostic Laboratory System Fresno Branch Laboratory University of California
This case report is a combination of two articles recently published in Avian Diseases (1,2) and compares the clinical history and signs, necropsy findings, microbiological findings and histopathological lesions of the brain associated with Mycoplasma gallisepticum (MG) and M. synoviae (MS) infections in turkeys. MG was isolated from the brain of 12-to-16-week-old turkeys showing severe central nervous system signs and mild respiratory problems. Necropsy revealed mild to severe airsacculitis in most cases. MG was isolated from the respiratory system (trachea, air sacs, and infraorbital sinuses) and from the brains. Histologically, there was moderate-to-severe encephalitis with lymphoplasmacytic cuffing of vessels, fibrinoid vasculitis, focal parenchymal necrosis, and meningitis. These lesions have been previously described, though, most current literature neglects to mention them. In contrast, we reported the first case of MS causing such lesions in the brains of turkeys (2). MS has been shown to cause systemic vasculitis in chickens, though this was not yet reported in turkeys. MS was isolated from the brains, trachea and joints of 22-week-old turkeys displaying severe synovitis and infrequent central nervous system signs. Histological examination of the brains revealed mild-to-severe meningeal vasculitis ranging from fibrinoid necrosis with little inflammation to marked lymphoplasmacytic cuffing which also involved the surrounding meninges. The only histological difference seen between the MG and MS infections was that there was infrequent involvement of the parenchymal vessels with MS, even in the few cases that had severe infarction of brain parenchyma.
Chin, RP, BM Daft, Cu Meteyer, and R. Yamamoto. Meningoencephalitis in commercial meat turkeys associated with Mycoplasma gallisepticum. Avian Dis. 35:986-993. 1991.
Chin, RP, CU Meteyer, R. Yamamoto, HL Shivaprasad, and PN Klein. Isolation of Mycoplasma synoviae from the brains of commercial meat turkeys with meningeal vasculitis. Avian Dis. 35:631-637. 1991.
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