Detection of Mycoplasma Synoviae and Other Pathogens in Laying Hens with Respiratory Signs in the Rearing and Production Phases

ABSTRACT The present study aimed to investigate the occurrence of Mycoplasma synoviae (MS), M. gallisepticum (MG), Ornitobacterium rhinotracheale (OR), Avibacterium paragallinarum (AP), Pasteurella multocida (PM) and Infectious Bronchitis Virus (IBV) in laying hens with respiratory clinical signs in two phases of production. 140 tracheal swabs and 140 blood samples were collected from laying hens in the rearing and production phases, the chickens belonged to six farms (A-F) located in the state of São Paulo, Brazil. The samples were analyzed by PCR for MG, MS, OR, AP, PM and IBV and by ELISA for MG and MS. The highest frequencies observed by PCR were for MS at farms B and C with 95 and 100% positivity, followed by MG at farms D and E with 35% and 65%, IBV with 35% at farm F and ORT with 15% at farm A. All flocks were positive for MG and MS in serology. Although MG and IBV have been detected, this can be explained by the vaccination protocols, since live attenuated vaccines are widely used for immunization against these pathogens. It was also possible to detect OR and AP thorugh PCR in some flocks. The occurrence of several etiological agents that cause respiratory diseases in laying hens was confirmed by PCR and serology, with MS being the most prevalent and being present in all farms studied.

摘要 本研究旨在调查处于生产两个阶段、表现出呼吸道临床症状的蛋鸡体内滑膜支原体（Mycoplasma synoviae, MS）、鸡毒支原体（M. gallisepticum, MG）、鼻气管炎鸟杆菌（Ornitobacterium rhinotracheale, OR）、副鸡禽杆菌（Avibacterium paragallinarum, AP）、多杀性巴氏杆菌（Pasteurella multocida, PM）及传染性支气管炎病毒（Infectious Bronchitis Virus, IBV）的感染情况。研究从巴西圣保罗州6个编号为A至F的养殖场中，采集了育雏期与产蛋期蛋鸡的140份气管拭子与140份血液样本。采用聚合酶链式反应（PCR）对样本开展MG、MS、OR、AP、PM及IBV的检测，并通过酶联免疫吸附试验（ELISA）检测MG与MS。PCR检测结果显示，B、C养殖场的MS阳性率最高，分别为95%与100%；其次为D、E养殖场的MG，阳性率分别为35%与65%；F养殖场的IBV阳性率为35%，A养殖场的OR阳性率为15%。所有受试鸡群的血清学检测均呈MG与MS阳性。尽管检出MG与IBV，但该结果可通过免疫接种方案得到合理解释：当前针对这两类病原体的免疫防控广泛使用弱毒活疫苗。部分鸡群还通过PCR检测出OR与AP阳性。本研究通过PCR与血清学检测证实，多株可引发蛋鸡呼吸道疾病的病原均存在感染；其中MS的感染率最高，且在所有受试养殖场中均有检出。