摘要
2017年5月21日,陕西省榆林市某养殖场的蛋鸡出现异常死亡。经国家参考实验室确诊,该起疫情为H7N9流感疫情。为找出引发疫情的可能原因,采用描述性流行病学方法,描述疫情的三间分布,分析发病的风险因素。调查结果显示:该场饲养规模较大,共有8栋鸡舍,饲养4.5万只蛋鸡;疫情暴发突然,病程仅为5 d;蛋鸡死亡2.2万只,死亡率为48.9%;疫情具有明显的场内传播规律,从靠近鸡场入口的鸡舍逐渐向内蔓延;产蛋高峰期蛋鸡的发病风险是雏鸡的37.458倍,差异显著(P<0.05);所分离毒株的HA基因裂解位点有4个氨基酸插入,为变异株;该起疫情可能是通过运输淘汰蛋鸡的车辆、野鸟、饲料和饮水,以及调入雏鸡等途径引入的。疫情发生后,当地政府按照《高致病性禽流感防治技术规范》,发布了封锁令,划定了疫点、疫区和受威胁区;在疫区采取了扑杀、无害化处理、关闭疫区内所有禽类产品交易市场等控制措施。采取以上处置措施后,疫情得以快速有效控制。
On May 21 st of 2017,abnormal deaths of some laying hens occurred in a farm of Yulin City,Shaanxi Province. After diagnosis by the national reference laboratory,the outbreak was confirmed as H7 N9 influenza. In order to find out the cause of outbreak,its three-dimensional distributions were described by descriptive epidemiological method,and risk factors of the disease were analyzed. The survey found that the farm was in a large scale with 8 chicken houses and 45 thousand laying hens. The outbreak was abrupt,and the disease course was only 5 days. A total of 22 thousand hens died,accounting for 48.9% of the total. There was an obvious law of field transmission,which meant the epidemic spread gradually from the hen house near the entrance of the chicken farm to the inside. The infection risk of laying hens at the peak of egg production was 37.458 times higher than that of baby chicks,and the difference was significant(P<0.05). The HA gene cleavage site of the isolated strain had 4 inserted amino acids,indicating the isolated strains were mutants. The epidemic might be caused by many infection sources and ways,such as the vehicles used for transporting culled laying hens,wild birds,feed,drinking water,introducing baby chicks,and so on. In response to the epidemic situation and according to the Technical Specifications for the Prevention and Control of Highly Pathogenic Avian Influenza,many control measures were carried out by local governments,including issuing the closure order,delimiting the infected point,infected area and threatened affected area,adopting the measures of culling and bio-safety disposal,closing all the poultry product trading markets in the epidemic area. At the end,the outbreak of H7 N9 influenza was controlled effectively.
出处
《中国动物检疫》
CAS
2018年第2期9-12,58,共5页
China Animal Health Inspection
基金
国家重点研发计划项目(2017YFC1200500)
关键词
家禽
H7N9流感
紧急流行病学调查
poultry
H7N9 influenza
emergency epidemiological investigation
