Clinical, Pathological and Molecular Study of Marek’s Disease in the Gallus gllus Domesticus and BrahmaChickens of Basra Province, Iraq

Abstract

The current study was conducted to diagnose the Marek’s disease in naturally infected Gallus gllusdomesticus chickens and Brahma chickens in Basrah province , Iraq, on the basis of clincopathological findings and by Polymerase chain reaction (PCR) . Suspected samples were collected randomly from different areas in Basrah province, (poultry houses, veterinary clinics, markets and Consulting clinic of the veterinary medicine college of Basrah university). The results of this study showed that some birds had significant clinical signs of Marek’s Disease, like paralysis of the legs and wings. Post mortem inspection showed different lesions according to chickens species in the Gallus gallusdomestics which were severely affected in sciatic nerve inferred by enlargement of sciatic nerve, splenomegaly & hepatomegaly with nodular tumor as well as lesions in the other organs. In Brahma chickens there were mild gross lesions in viscera and only showed enlargement of sciatic nerve. Histopathological examination showed changes in the spleen (necrosis in the white pulp and hyperplasia in the central arteriole of the white pulp) . Sciatic nerve showed edematous fluid in the nerve parenchyma and infiltration of mononuclear inflammatory cells mainly lymphocytes in the nerves parenchyma. The feather follicleshowed marked vaculationof the epithelial layer as well as infiltration of inflammatory cells in the follicular lining. The confirmation was doneby PCR which showed that the total positive samples for avian Marek’s Disease serotype-1 were nine samples,three positive samples of spleens and two positive samples of feather follicles as well as three positive samples of sciatic nerve and one positivesample of liver . Based on these results , MDV was concluded to be the etiology for this pathological condition in Iraqi backyard flocks. This is the first report of the presence of the MDV in Gallusgallus and Brahma breed in Iraq. Accordingly, the commercial poultry population in Iraq is not far from the threat of the MDV, and surveillance for MDV is needed.