Application of different diagnostic techniques in detection and estimation of prevalence of avian influenza in poultry of Chattogram region

Abstract

Avian influenza (AI) is an infectious disease of birds caused by influenza A virus, posing a major global public health and economic concern. In Bangladesh, AI outbreaks in commercial and backyard poultry are frequent and cause huge losses in the poultry industry. This study was conducted to detect avian influenza virus (AIV) in layer poultry farms of Chattogram region by using molecular techniques and to study the pathological alterations in AIV-infected birds. A total of 108 pooled samples were collected from 26-layer farms. Gross and histopathological examinations were performed for assessing pathological changes. RNA was extracted and after cDNA conversion subjected to conventional PCR. Real-time RT-PCR was also performed targeting the M gene for AIV detection. Out of 26-layer farms, 3 were found positive for AIV based on rRT-PCR, although 6 farms were positive by conventional PCR. On the other hand, gross lesions suggestive of AIV infection were observed in birds from 8 farms (30.8%). Gross lesions included erythema and congestion in abdominal skin, hemorrhages in trachea and lungs, hemorrhage on the fat of abdomen and coronary groove of heart, enlarged spleen, and necrosis in intestine. In case of laying hen, the ova were hemorrhagic and misshapen. Histopathological changes comprised epithelial desquamation, inflammatory cell infiltration, congestion, hemorrhages, and necrosis in respiratory and digestive organs. This study confirms the AIV in layer poultry of Chattogram and provides valuable insights into the associated pathological alterations. The findings highlight the urgent need for continuous surveillance and effective control strategies against AIV to safeguard poultry health and production in Bangladesh.