Highly pathogenic avian influenza virus subtype H5N1 in ducks in the Northern part of Cameroon

Highly pathogenic avian influenza (HPAI) virus was first detected in Cameroon in February 2006. Analysis of NA sequences of the virus demonstrated that it is closely related to the H5N1 isolates from Northern Nigeria, Sudan and Ivory Coast, suggesting a common virus ancestor.     

Experimental infection of chickens, ducks and quails with the highly pathogenic H5N1 avian influenza virus

Highly pathogenic avian influenza viruses (HPAIV) of the H5N1 subtype have spread since 2003 in poultry and wild birds in Asia, Europe and Africa. In Korea, the highly pathogenic H5N1 avian influenza outbreaks took place in 2003/2004, 2006/2007 and 2008. As the 2006/2007 isolates differ phylogenetically from the 2003/2004 isolates, we assessed the clinical responses of chickens, ducks and quails to intranasal inoculation of the 2006/2007 index case virus, A/chicken/Korea/IS/06. All the chickens and quails died on 3 days and 3-6 days post-inoculation (DPI), respectively, whilst the ducks only showed signs of mild depression. The uninoculated chickens and quails placed soon after with the inoculated flock died on 5.3 and 7.5 DPI, respectively. Both oropharyngeal and cloacal swabs were taken for all three species during various time intervals after inoculation. It was found that oropharyngeal swabs showed higher viral titers than in cloacal swabs applicable to all three avian species. The chickens and quails shed the virus until they died (up to 3 to 6 days after inoculation, respectively) whilst the ducks shed the virus on 2-4 DPI. The postmortem tissues collected from the chickens and quails on day 3 and days 4-5 and from clinically normal ducks that were euthanized on day 4 contained the virus. However, the ducks had significantly lower viral titers than the chickens or quails. Thus, the three avian species varied significantly in their clinical signs, mortality, tissue virus titers, and duration of virus shedding. Our observations suggest that duck and quail farms should be monitored particularly closely for the presence of HPAIV so that further virus transmission to other avian or mammalian hosts can be prevented.     

Risk Analysis of Wild Birds in Spread of Highly Pathogenic Avian Influenza

Outbreaks of highly pathogenic avian influenza （HPAI） H5N 1 have taken place in 15 countries in Asia, Europe and Africa since 2003, and have caused great economic losses. Much likelihood has been considered as risk factors, of which wild birds are attributed as one of the main factors. This is related to the environmental deterioration in the wetland and expanse of human＇s activities in production. The risk analysis in this paper only focused on the effect of wild birds to HPAI, and confirmed the high risk of wild birds in the spread of AIVs.     

2020年山东省淄博市高致病性禽流感监测

为掌握山东省淄博市高致病性禽流感(H5N1 Re-11/Re-12株)免疫效果、病原分布及防控情况,根据2020年淄博市动物疫病监测与流行病学调查计划要求,按照两阶段抽样法从全市规模养殖场和散养户中随机抽取血清和棉拭子样品,采用血凝(HA)和血凝抑制(HI)、荧光RT-PCR方法进行抗体和抗原检测,并对检测结果进行统计...     

H5亚型禽流感灭活油乳剂疫苗对鸭的免疫试验

H5亚型禽流感(AI)油乳剂灭活疫苗接种成年鸭和幼鸭后,用ELISA法检测抗体消长规律,结果表明,AIVH5亚型灭活油乳剂疫苗两次接种可以有效地预防成年鸭,而一剂H5亚型AIV灭活油乳剂疫苗接种幼鸭后的免疫应答反应不好。     

中国高致病性禽流感免疫预防风险评估

疫苗接种是当前我国预防和控制HPAI疫情的有效手段之一.由于影响HPAI免疫预防效果的因素众多,会给免疫预防带来风险.对这些风险因子进行识别,并系统分析其所引起的风险程度的高低,进而采取针对性的风险管理措施,能有效提高免疫预防的效果.本研究首次运用层次分析法（Analytic Hierarchy Process, AHP）构建了HPAI免疫预防风险评估模型,通过确定风险因子权重,依权重大小对风险因子进行排序,确定风险等级.分析结果表明：管理不良、接种操作不规范、实验室监测等是我国免疫预防的高风险因素.通过对免疫预防风险进行综合分析,为HPAI免疫预防管理和决策提供了科学依据.     

全球高致病性禽流感风险评估

H5N1高致病性禽流感暴发的风险管理需要对不同的风险因素进行综合评估,这些因素影响不同地理区域传染病的传播和持续时间。禽流感灾害风险评估的关键是制定风险路径,然后用它来发展一种定性或定量的风险评估模型。本文建立在风险分析模型框架基础之上,利用FAO、WHO以及OIE等国际组织和有关国家政府可公开获得的数据和信息,利用ArcGIS对H5N1高致病性禽流感进行风险评估,并对野生鸟类和家禽贸易在H5N1高致病性禽流感传播中的重要性进行分析。     

Seroprevalence of low pathogenic avian influenza (H9N2) and associated risk factors in the Gyeonggi-do of Korea during 2005-2006

Between November 2005 and March 2006, a total of 253 poultry flocks in the Gyeonggi-do of Korea were examined for seroprevalence against avian influenza (AI) using a hemagglutination inhibition (HI) test and an agar gel precipitation test. No low pathogenic avian influenza (LPAI) virus was isolated from 47 seropositive flocks that lacked clinical signs during sampling. The unadjusted percentage of seroprevalence rates of layer and broiler flocks were not significantly different, i.e., 26% (25/96) and 23% (22/97), respectively. The HI titer of the layers (mean = 89) was higher than the broilers (mean = 36; p < 0.001). A cross-sectional study was conducted for the seroprevalence of LPAI in the layers. Of 7 risk factors, farms employing one or more workers had a higher seropositive prevalence as compared to farms without hired employees (adjusted prevalence OR = 11.5, p = 0.031). Layer flocks older than 400 d had higher seropositivity than flocks younger than 300 d (OR = 4.9, p = 0.017). The farmers recognized at least one of the clinical signs in seropositive flocks, such as decreased egg production, respiratory syndromes, and increased mortality (OR = 2.3, p = 0.082). In a matched case-control study, 20 pairs of case and control flocks matched for type of flock, hired employees, age, and flock size were compared. Frequent cleansing with disinfectants was associated with a decreased risk of seropositivity (OR = 0.2, p = 0.022). Although there was a low statistical association, using a foot disinfectant when entering the building led to a decreased rate of seropositivity (OR = 0.3, p = 0.105).