Pathological Studies on Natural Infection With Avian Influenza Virus In Domestic Birds

Our study emphasizes the importance of understanding the pathogenicity ofavian influenza virus in different domestic birds through reporting in detailedpathological lesions in different organs of chicken, duck and turkey in order tostate the species variations in pathogenecity. The birds focused in this study werethe naturally infected birds with avian influenza virus. Samples collected frompoultry flocks included a total number of 126 birds collected from 37 chickenflocks (27 broiler and lO layer flocks); 38birds collected from 9 duck flocks; and11 birds collected from 5 turkey flocks. All of these collected birds had beenanalyzed for influenza virus then only the positive infected cases had proceededinto detailed histopathological examination. 68.4% of duck birds, 63.6% of turkeypoults, 73.1 % of broilers and 81.8% of layers were positive for influenza virusesusing hemagglutination, hemagglutination inhibition tests and rt-Pf.R, All thepositive specimens were H5N1. We had assessed the average severity of avianinfluenza gross and histological lesions in different sampled birds semiquantitatively negative (no lesion detected), mild, moderate, or marked.For commercial and backyard duck flocks, in the past, ducks have beenconsidered to be clinically resistant to HP AI viruses with no clinical disease ormortality, although virus has been shown to spread systemically in experimentallyinfected ducks. Recent experimental studies and field observations have reportedthe increased pathogenesis and mortality of the currently circulating H5Nl HP AIvirus in both domestic ducks and wild birds. The two most prominent clinical signsreported among the infected flocks were increased mortality rates and neurologicaldisorders. The major gross lesions reported were red-brown mottling of thepancreas, moderately enlarged spleen, mildly to moderately congested and