规模化肉鸡场常见呼吸道病原体感染状况调查

Epidemic Investigation for the Infection Avian Respiratory Disease Pathogens from a Large-scale Chicken Farm

呼吸道疾病尤其是常见的禽流感、新城疫、传染性支气管炎是危害养鸡业最严重的疾病之一。为了解肉鸡初期呼吸道病病原体的感染状况,从2万孵化的鸡胚中采集了210枚弱、死胚样品及5日龄有呼吸道症状的48只病死鸡。用RT-PCR方法对这两批样品进行了H9N2亚型禽流感病毒(H9N2AIV)、新城疫病毒(NDV)、传染性支气管炎病毒(IBV)感染状况的检测,又将5日龄的雏鸡进行了大肠杆菌(Escherichia coli)及沙门氏菌(Salmonella spp.)分离鉴定,分析检出率。结果表明,在210枚鸡胚样品中H9N2 AIV、NDV和IBV的检出率分别为3.81%,21.9%和23.8%,弱、死胚样品常见呼吸道病病毒感染率高达49.51%。5日龄雏鸡样品中H9N2AIV、NDV、IBV、E.coli和S.spp.的检出率分别为45.8%,37.5%、10.4%、54.2%和8.3%,未发现3种病毒共感染的现象,但是病毒与细菌的共感染率达58.3%,主要是大肠杆菌与病毒的双重感染。呼吸道病毒一般能将鸡胚在孵化过程中致死,但若含病毒的鸡胚没能死亡,雏鸡出壳后发育到一定时期(母源抗体衰竭后)所含病毒会大量复制,进而发生相应的呼吸道疾病,在鸡群中迅速传播,并继发其他细菌性疾病,造成鸡群大批死亡,这是肉鸡中后期呼吸道疾病日益严重的重要原因。

Avian respiratory infection plays a prominent role in damaging the poultry industry, especially the Avian flu,Newcastle disease and chicken infectious bronchitis. 210 lung samples of dead or weak broiler embryo and 48 lung and liver samples of broilers with respiratory symptoms were collected from a large-scale broiler farm, and then RT-PCR was used to detect H9N2 subtype of Avian influenza virus（H9N2 AIV）, Newcastle disease virus（NDV） and infectious bronchitis virus（IBV）, Escherichia coli and Salmonella spp. were separated from 48 chicks. The results show that the detection rates of the three pathogens of the 210 lung samples of embryo were 3.81%（H9N2 AIV）, 21.9%（NDV）, 23.8%（IBV） and respiratory tract viral infection rates were up to 49.51%. The detection rates of the five pathogens of the 48 lung and liver samples of broilers were 45.8%（H9N2 AIV）, 37.5%（NDV）, 10.4%（IBV）, E. coli（54.2%）, S. spp.（8.3%） and the co-infection of the three virus were not detected, while the ratio of co-infection between virus and bacteria was up to 58.3% especially E. coli played an important role in the co-infection. The chicken embryos were easier to die during incubation with respiratory viral,but if not die the chicks developed to a certain period（the maternal antibody failure） while the virus could proliferation then respiratory diseases would happen and spread rapidly in chicken flocks with bacterial infection resulted in a large number of deaths, which is an important cause of late respiratory illness increasingly serious in broiler chickens.