Pathological characterization, viral isolation and molecular detection of Newcastle disease virus in small scale poultry farms in Bishoftu Town, Central Ethiopia.
No Thumbnail Available
Date
2023
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Addis Abeba University
Abstract
Poultry diseases are among the major constraints of chicken production in Ethiopia. Of which Newcastle disease (ND) is still one of the most important devastating diseases of chicken. Cross sectional study was conducted from November 2022 to May 2023 on clinically sick chickens to characterize lesions due to Newcastle disease, and to isolate the Newcastle disease virus, in 53 small scale farms of Bishoftu town. Questionnaire survey was done to evaluate farm biosecurity in farms that have had clinical diseases. Necropsy was done on a total of 120 chickens. Viral isolation was done on cell culture and detection of the viral genome was done by reverse transcriptase PCR. A total of 53 pooled tracheal and cloacal swab and tissue specimens were sampled from sick chickens showing clinical signs of Newcastle disease and from apparently healthy chicken that have had contact with diseased chicken. Out of 53 collected pools of swab
and tissue samples, 24 pools (45.3%) were positive for Newcastle disease virus by real-time PCR. Newcastle disease virus was isolated from suspected cases in all ―kebele‖ or county with the proportions of isolation of 11.32% for Dembi kebele, 3.77% for Filtuu, 5.66% for Qurqura, 1.89% for Kata, 5.66% for Gorba, and 9.43% for Calalaka. Depression, greenish or white diarrhea, torticollis, labored breathing, respiratory rales and drop in egg production with softshelled
egg were commonly observed signs. Hemorrhagic lesions in the proventriculus, intestine, cecal tonsils, and hemorrhagic tracheitis were the common grossly seen lesions. The spleens were enlarged, friable and dark red or mottled, while the kidneys were enlarged, congested and swollen. Among the microscopic lesions were necrosis of the proventriculus mucosal epithelium with mononuclear cell infiltration into the lamina properia; Cecal tonsil hemorrhages, and
lymphoid depletion; tracheal mucosa epitheliums necrotized with loss of cilia and interstitial pneumonia. Bursa of fabricates showed lymphocyte necrosis, and cystic structure and interfollicular epithelial hyperplasia. Heart showed myocarditis, and myocardial necrosis. Kidneys showed swelling, pale necrotic areas and microscopic lesions include hemorrhages into the interstitium and renal tubular epithelial cell necrosis. Brain grossly showed encephalitis and hemorrhage, microscopically excessive lymphocytes in and around brain capillaries and multifocal hemorrhages. Based on findings, it could be concluded that Newcastle disease is causing death of chickens, reduced egg production and causes economic loss in the study area. Prevention
Description
Keywords
Bishoftu, Newcastle Disease, Pathology, Poultry