Etiopathological studies on low pathogenic avian influenza and molecular detection of concurrent infections in broiler chicken

Abstract

The present study was carried out to investigate the mortality in broiler chicken due tolow pathogenic avian influenza (LPAI) and concurrent infections of infectious bronchitis (IB) virus, avian mycoplasma and Escherichia Coli. The study comprised of flock wise mortality, gross and histopathological examination of trachea, bronchi, lung and air sacs and molecular detection of LPAI (H9N2), IB virus, Mycoplasma Gallisepticum (MG) and Mycoplasma Synoviae (MS) and avian pathogenic E. coli (APEC) from pooled samples of bronchi containing caseous plugs from thirty broiler flocks. The mortality among these flocks ranged between 1.26 to 9.08 percent with an average of 3.20 percent per flock. Gross and histopathological lesions were predominantly found in trachea, bronchi, lungs and air sacs. All the flocks (100%) were found positive for LPAI (H9N2) virus as well as for pathogenic E.coli, whereas IB virus, M. gallisepticum (MG), M. synoviae (MS) were detected form 6 (20%), 11 (36.67%), and 3 (10%) flocks, respectively. Molecular characterization of E. coli for the detection of virulence genesrevealed 27 (90%) cases positive for presence of iss gene followed by 25 (83.33%) for vat gene, 15 (50%) for tsh gene and 10 (33.33%) for papC gene. It was concluded that among different respiratory pathogens, mixed infections of LPAI, E. coli and M. gallisepticum were consistent in tracheo-bronchitis with caseous plugs, leading to increased mortality in the broilers.