PREVALENCE AND PATHOLOGY OF AVIAN PATHOGENIC ESCHERICHIA COLI INFECTION IN BACKYARD NATIVE CHICKEN

Abstract
A study was conducted during the period of one year to record the prevalence of infectious diseases in native chicken reared in and around Chennai. A total of four hundred and twenty one necropsies were carried out from dead birds collected from different organized and unorganized poultry farms in and around Chennai. Death due to bacterial origin (43.22%) were the highest among the native chicken with Escherichia coli infection (27.5%) being the highest followed by, Pasteurella infection (12.86%) and Staphylococcal infection (2.86%) either as single or co-infections. Fibrinous pericarditis, fibrinous perihepatitis, mild splenic enlargement, mild pneumonic changes and catarrhal enteritis were the gross lesions observed in Escherichia coli affected cases. Microscopic changes included hepatic sinusoidal congestion, hepatocellular degeneration with capsular thickening, edema, abundant eosinophilic fibrinous exudate, heterophilic and macrophage infiltration with presence of multinucleated giant cells. Masson’s trichrome special staining method revealed the presence of fibrinous strands over the surface of the liver and heart. Epicardium was thickened with necrosis of myocardial cells, oedema, hemorrhages, endothelial cell showed proliferation and abundant fibrinous exudate surrounded by heterophils, macrophages and multinucleated giant cells with bacterial colonies revealing bacteremia. Multifocal congestion, hemorrhage and edema were noticed in the parabronchi.
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