高致病性禽流感与天气条件分析

利用全国气象观测资料、NCEP／NCAR日平均再分析数据资料集和我国高致病性禽流感疫情资料,分析高致病性禽流感发生的时空特征以及与天气条件的关系。结果表明,我国高致病性禽流感全年可以发生,疫情的分布范围广,大部分地区都有出现。发生和传播与环境气象条件有关,季节性明显,冬季和秋季为主要发病季节。冬季禽流感发生前高空500hPa以槽为主,冷空气活动频繁。发生日基本在高压系统的控制之下,地面流场呈辐散状,风速稳定少变。     

The indirect immunofluorescence assay using cardiac tissue from chickens, quails and ducks for identification of influenza A virus during an outbreak of highly pathogenic avian influenza virus (H5N1): a rapid and simple screening tool for limited resource settings

Here we describe the diagnostic utility of the indirect immunofluorescence assay (IFA) during a recent outbreak of highly pathogenic avian influenza (HPAI) subtype H5N1 virus in southern Thailand and demonstrate the usefulness of the cardiac tissue from infected chickens, quail, and ducks for diagnosis. The most reliable sample for IFA diagnosis of influenza A virus was cardiac tissue (83.0%; 44/53) which when divided by species (chicken, quail and duck cardiac tissues) gave respective positivity rates of 88% (22/25), 88.9% (16/18) and 60.0% (6/10). Cardiac tissue also gave the highest IFA intensity for the three species. We believe that the IFA method has wide applicability in developing countries or remote settings where clinically similar avian diseases with high morbidity and mortality such as Newcastle disease and fowl cholera are common and could be rapidly excluded thereby conserving valuable reference laboratory capacity for true HPAI outbreaks.     

白羽肉鸭高致病性禽流感疫苗免疫效果研究

对白羽肉鸭高致病性禽流感疫苗免疫效果进行了试验研究,结果表明,白羽肉鸭如能按照免疫程序规范实施免疫操作,能够获得较好的免疫效果,首免剂量以0．5-0．8mL为宜。     

山东省首起野生天鹅H5N8高致病性禽流感疫情的紧急调查及处置

2021年1月12—19日,山东黄河三角洲国家级自然保护区大汶流管理站出现35只死亡的野生疣鼻天鹅.经现场调查,市级和省级实验室检测,诊断为疑似H5N8亚型高致病性禽流感,经国家禽流感参考实验室进行病毒分离鉴定,最终确定为H5N8亚型高致病性禽流感疫情.疫情发生后,通过现场调查、座谈及实验室检测等方式,对此次疫情开展了...     

Development of Disease‐specific,Context‐specific Surveillance Models: Avian Influenza (H5N1)‐Related Risks and Behaviours in African Countries

Avian influenza virus (H5N1) is a rapidly disseminating infection that affects poultry and, potentially, humans. Because the avian virus has already adapted to several mammalian species, decreasing the rate of avian–mammalian contacts is critical to diminish the chances of a total adaptation of H5N1 to humans. To prevent the pandemic such adaptation could facilitate, a biology‐specific disease surveillance model is needed, which should also consider geographical and socio‐cultural factors. Here, we conceptualized a surveillance model meant to capture H5N1‐related biological and cultural aspects, which included food processing, trade and cooking‐related practices, as well as incentives (or disincentives) for desirable behaviours. This proof of concept was tested with data collected from 378 Egyptian and Nigerian sites (local [backyard] producers/live bird markets/village abattoirs/commercial abattoirs and veterinary agencies). Findings revealed numerous opportunities for pathogens to disseminate, as well as lack of incentives to adopt preventive measures, and factors that promoted epidemic dissemination. Supporting such observations, the estimated risk for H5N1‐related human mortality was higher than previously reported. The need for multidimensional disease surveillance models, which may detect risks at higher levels than models that only measure one factor or outcome, was supported. To develop efficient surveillance systems, interactions should be captured, which include but exceed biological factors. This low‐cost and easily implementable model, if conducted over time, may identify focal instances where tailored policies may diminish both endemicity and the total adaptation of H5N1 to the human species.     

Risk factors and characteristics of H5N1 Highly Pathogenic Avian Influenza (HPAI) post-vaccination outbreaks

Highly pathogenic avian influenza (HPAI) virus H5N1 is now endemic in South-East Asia but HPAI control methods differ between countries. A widespread HPAI vaccination campaign that started at the end of 2005 in Viet Nam resulted in the cessation of poultry and human cases, but in 2006/2007 severe HPAI outbreaks re-emerged. In this study we investigated the pattern of this first post-vaccination epidemic in southern Viet Nam identifying a spatio-temporal cluster of outbreak occurrence and estimating spatially smoothed incidence rates of HPAI. Spatial risk factors associated with HPAI occurrence were identified. Medium-level poultry density resulted in an increased outbreak risk (Odds ratio (OR) = 5.4, 95% confidence interval (CI): 1.6–18.9) but also climate-vegetation factors played an important role: medium-level normalised difference vegetation indices during the rainy season from May to October were associated with higher risk of HPAI outbreaks (OR = 3.7, 95% CI: 1.7–8.1), probably because temporal flooding might have provided suitable conditions for the re-emergence of HPAI by expanding the virus distribution in the environment and by enlarging areas of possible contacts between domestic waterfowl and wild birds. On the other hand, several agricultural production factors, such as sweet potatoes yield, increased buffalo density, as well as increased electricity supply were associated with decreased risk of HPAI outbreaks. This illustrates that preventive control measures for HPAI should include a promotion of low-risk agricultural management practices as well as improvement of the infrastructure in village households. Improved HPAI vaccination efforts and coverage should focus on medium poultry density areas and on the pre-monsoon time period.     

辽宁省一起野禽H5N6高致病性禽流感疫情的紧急流行病学调查

2021年4月6日,辽宁省沈阳市和平区长白岛森林公园内饲养的10只黑天鹅和1只大雁死亡,袭击率为3.8％(11/291).经现场调查和临床剖检诊断,市级和省级疫病控制中心实验室检测,诊断为疑似H5亚型高致病性禽流感.随后,经国家禽流感参考实验室确诊为H5N6亚型高致病性禽流感.4月12日,农业农村部公布了该起疫情.在接...     

Qualitative risk assessment of transmission pathways of highly pathogenic avian influenza (HPAI) virus at live poultry markets in Dhaka city,Bangladesh

Analysis of environmental samples obtained from the Live Poultry Markets (LPMs) of Dhaka City, Bangladesh, has revealed that the highest degree of prevalence of highly pathogenic avian influenza A (HPAI, H5N1), besides other subtypes of the LPAI virus, poses the plausible risk of transmission of these viruses between human and poultry species. The present study was conducted using the OIE risk analysis framework to assess the risk level of each pathway successively. The estimated risk parameters were integrated towards to obtain the overall risk level for each specific HPAI transmission pathway using the matrix adapted by Cristobel Zepeda accompanying other expert consultations. The relevant data obtained from published and unpublished sources, together with survey data of field observations, were used to formulate and confirm the risk pathways and their associated risks. The results revealed that the risk of the release of the HPAI virus was medium when exposure was high. Additionally, the consequence would be considered very high with a medium degree of uncertainty for all parameters. Ultimately, the overall risk for transmission was estimated as medium with a medium degree of uncertainty. The findings of this study reveal that there is a significant threat that HPAI virus transmission could occur among poultry and humans and effectively sustain within the environment of the LPMs. Our findings are primarily focused on public health considerations, the hygienic slaughter of poultry and the relevant cleaning and sanitation practices conducted in the LPMs to support evidence‐based decision‐making processes. The findings of the study have the potential to be used to formulate effective risk reduction measures and can be further adapted in low‐resource settings without major infrastructural changes required of the LPMs. All of which would reduce the risk of HPAI virus release and further lessen the degree of exposure and transmission in established LPMs.     

禽流感的启示

禽流感是一种毁灭性疾病，每一次严重的爆发都会给养殖业造成巨大的损失，对国民经济乃至整个世界经济产生重大影响。禽流感的流行不但严重影响养禽业的发展，还波及到猪肉、牛肉和羊肉市场，进一步影响到畜牧业生产，甚至危害到人类健康。本文就禽流感大面积的持续流行，分析我国目前禽病防制中存在一系列问题并提出相应的对策。     

华北地区高致病性禽流感与气象条件分析

利用中国大陆高致病性禽流感疫情资料、NCEP/NCAR日平均再分析数据资料集以及华北地区气象站地面观测资料,研究了华北地区高致病性禽流感发生与气象条件的关系。结果表明,华北地区高致病性禽流感主要发生在秋冬季。发生前期,高致病性禽流感发生地区冷空气活动频繁,气温较低且波动明显,前期或同期高致病性禽流感发生地外界环境较为湿润。此外,合适的风向风速可能有利于烈性传染病高致病性禽流感向周边地区扩散和传播。