- 期刊
病例報告：產蛋雞傳染性貧血症
Case Report: Chicken Infectious Anemia in Layers
摘要
屏東縣鹽埔鄉某一蛋中雞場，發病雞舍共飼養5000隻蛋雞，雞齡九週齡，其中發生貧血症狀的雞隻約80%（4000/5000），連續死亡約55%（2200/4000 ）。病雞外觀可見精神沉鬱、佇立、雞冠呈淡粉紅色、腳部呈淡黃色之貧血症狀，檢測病雞血液結果血容比（PCV）下降至3-12%，病雞剖檢可見胸部及腿部肌肉散發性出血斑、心肌出血斑、胸腺及華氏囊萎縮、骨髓呈黃白色並且含有脂肪。組織病理切片下可見骨髓造血母細胞流失，胸腺及華氏囊淋巴細胞流失。採取病雞骨髓及肝臟萃取病毒DNA並以聚合酶鏈鎖反應（PCR）檢測，結果分別於肝臟、骨髓及腎臟可得到分子量400 bp單獨之病毒核酸片段，且經定序後證實本爆發病例為雞傳染性貧血感染症。同時本病例中有些發病雞隻之臟器可分離到大腸桿菌（E. coli），此乃因為雞隻貧血及免疫抑制所引發之細菌性二次感染。以往的文獻報告中，雞傳染性貧血常發生於較幼齡的雞隻，而本病例則發生於較成熟之蛋中雞，頗值得報告及進一步深入探討。
並列摘要
Chicken infectious anemia (CIA) is caused by avian circovirus and commonly affects the young susceptible chickens with clinical signs of severe anemia and immunosupression in the commercial producing farm. This outbreak case was reported from a farm raised about 5000 layers in Pingtung County. The morbidity of this outbreak was 80% (4000/5000) and the mortality was about 55% (2200/4000) when layers were at the age of 9 weeks old. Affected layers showed anorexia, depression and with obviously clinical signs of pale in the crest, face and foot. In addition, the clotting time from affected layers blood samples was increased and blood plasma was more translucent than normal and the packed cell volume (PCV) range significantly dropped to 3-12%. The gross lesions of hemorrhage could be observed in the muscles of chest, legs and heart. Moderate to severe atrophy on thymus and bursa of Fabricius were also noticed. Moreover, the color of bone marrow showed pale to yellowish with fatty infiltration. Histopathologically, the number of myeloid and hematopoietic cells showed depletion and replaced by adipose tissue in bone marrow from anemic layers. Furthermore, the total DNA of liver, thymus and bone marrow were extracted respectively from infected layers and analyzed by polymerase chain reaction (PCR) method. The sequencing results indicated an identical 400-bp amplicons of CIA virus were found from the infected samples. The secondary E. coli infections were also noticed from some anemic layers due to severe anemia and immunosupression. This outbreak case demonstrated that 9 weeks old layers were susceptible to CIA virus although the infection was mostly reported in young chicks.