2019年安徽省A型禽流感病毒群体流行率横断面研究

Cross-sectional Studies on Herd Prevalence of AIV Type A in Anhui Province in 2019

为掌握安徽省A型禽流感病毒(avian influenza virus,AIV)感染情况,2019年春季和秋季开展了两次横断面研究。用估计流行率方法,每次随机选取包括种禽场、蛋禽场、肉禽场、活禽批发市场、农贸市场、自然村和野禽栖息地在内的约193个场点,再用发现疫病抽样策略,在每个场点采集20份家禽咽喉-泄殖腔双拭子、环境拭子或野禽粪便棉拭子样品,使用荧光RT-PCR检测试剂盒进行A型AIV核酸检测,对检测阳性的再进行H5、H7和H9亚型分型。结果显示:春、秋两季AIV群体表观流行率分别为17.9%、12.6%,群体真实流行率分别为16.4%(95%CI:11.2%~21.6%)、10.4%(95%CI:6.1%~14.7%);春、秋两季在规模养殖场、自然村散养户、活禽批发市场和农贸市场均检出了A型AIV,其中H9亚型阳性率分别为6.2%、4.2%,未检出H5、H7亚型;A型AIV流行率无地理和季节上的显著差异(P> 0.05),但春、秋两季的活禽市场流行率比(prevalence ratio,PR)分别是养禽场的2.2倍(95%CI:1.2~4.2)、2.3倍(95%CI:1.1~5.0)。结果表明,2019年春、秋两季A型AIV在安徽省养殖和交易环节均存在不同程度的污染,其中交易环节流行风险较大,因此要特别注重活禽交易市场和农贸市场的禽流感防控。

In order to identify the status of prevalence of avian influenza virus type A(AIV-A)in Anhui Province,two cross-sectional studies were conducted in the spring and autumn of 2019 separately.A total of 193 premises including breeding farms,layer farms,commercial broiler farms,wholesale markets,markets for agricultural products,natural villages and wild bird habitats were selected by the estimated prevalence method.Then,20 throat/cloacal,environmental or wild birds’feces swab samples were collected from each premise by taking the sampling strategy of disease detection to detect AIV-A nucleic acids by real-time RT-PCR,for the positive samples,H5,H7and H9 subtypes were further typed.The results showed that,the apparent prevalence rates of AIV at herd level were 17.9%and 12.6%respectively in the spring and autumn,and the real prevalence rates were 16.4%(95%CI:11.2%-21.6%)and 10.4%(95%CI:6.1%-14.7%)respectively;AIV-A was detected out in scaled farms,households,wholesale markets and markets for agricultural products in the spring and autumn,in which,the positive rates of H9 subtype were 6.2%and 4.2%respectively,and no H5 or H7 subtype was detected out;there was no significant difference in the prevalence of AIV-A in terms of geography and seasons(P>0.05),but that in poultry markets was 2.2(95%CI:1.2-4.2)and 2.3(95%CI:1.1-5.0)times as high as poultry farms respectively in spring and autumn.As a conclusion,the processes of poultry production and trading were infected with AIV-A to different extent in spring and autumn of 2019,especially during trading,so a top priority should be given to prevent and control avian influenza in poultry markets and markets for agricultural products.