Estimation the viral load and pathology of high pathogenic avian influenza virus (H5N8) in chickens

Theaims of this study were detect the pathological changes and viral loadsofAIV subtype-H5 as the causative pathogen in the industrial broilers farm in Iraq.In Iraq in the last 2017 and early 2018 and 2019 the high pathogenic avian influenza A subtype H5N8 virus was detected in several regions, and cause a high economic losses for the poultry industry.Avian influenza H5N8 is an infectious disease that mainly causes extreme respiratory illness in poultry that is associated with a high percentage of morbidity and mortality in the infected chickens. One hundred and fifty collected samples (trachea and lung) from different parts of broiler chicken from Baghdad were obtained during this study and neighboring governorates during the winter of 2019.The results of RT-PCR of collected samples showed that only 12 out of 150 tested samples were positive for H5N8.Real Time RT-PCR is consider asensitive, rapid, and practical molecular technique for detection of avian influenza disease viruses.Avian influenza viral loads were estimated in tissues from infected chickensby using quantitative real time RT-PCRtechnique to calculate the viral particles in each samples.The main clinical finding include depression, lack of agitate, ruffling feathers, and increase mortality of chicken, redness of wattle, hemorrhage of legs and subcutaneous tissues, swollen and edema of the face severe rals, sinusitis, edema of the head and wattle with diarrhea and even sudden death.Cross pathogenic lesion in post-mortem examination of chickenrevealedthat is accumulation of small quantities of yellowish color sero-fibrinous exudates and the walls of the thoracic air sacs are covered with fibrin and thickened with notable congestion of capillary blood vessels.congestion and petechial hemorrhage of internal organs( intestine & pancreas ) with accumulation of sero-fibrinous exudate.