[Comparative study of infectious and atypical encephalomyelitis in birds]

Studied were morphologically a total of 234 birds for infectious encephalomyelitis (IE) and atypic encephalomyelitis (AE) of which 70 were experimentally infected with standard reference strains of IE (Calnek 1143-42 birds, and Van Roeckel 28 birds), 32 were infected with a brain suspension of affected with AE birds, and 110 were spontaneously affected with AE. Those of the birds that were infected with the standard strains of IE as well as with the brain suspension exhibited changes in the central nervous system in the form of a non-suppurative encephalomyelitis, and in the viscera--lymphoidcell proliferations. These alterations proved analogous with those observed in birds spontaneously affected with AE. The changes in CNS in the case of IE were localized in the brain and the spinal cord, while the lesions in the case of AE were found chiefly in the brain. In AE there were perivascular lymphoidcell were groupings along the peripheral nerves. It was concluded that the histologic changes established may well serve to differentiate IE from AE in Marek's disease, the transitional paralysis, the Newcastle disease, and the alimentary encephalomalacia.