Landman W J M, Germeraad E A, Kense M J
a GD - Animal Health , Deventer , Netherlands.
b Department of Virology , Wageningen Bioveterinary Research Lelystad , Netherlands.
Avian Pathol. 2019 Apr;48(2):98-110. doi: 10.1080/03079457.2018.1551612. Epub 2018 Dec 20.
An outbreak of low pathogenic avian influenza (LPAI) subtype H6N1 (intravenous pathogenicity index = 0.11) infection occurred in four productive brown layer flocks on three farms in the Netherlands within a period of two months. The farms were located at a maximum distance of 4.6 km from each other. The infections were associated with egg production drops up to 74%, pale eggshells and persisting high mortality up to 3.2% per week. Three flocks were slaughtered prematurely as they were not profitable anymore. Newcastle disease, infectious bronchitis, egg drop syndrome and Mycoplasma gallisepticum infections could very likely be excluded as cause of or contributor to the condition in the field. Also, the anticoccidial drug nicarbazin, which can cause egg production drops and eggshell decolouration, was not detected in eggs from affected flocks. Furthermore, post mortem examinations revealed no lesions indicative of bacterial infection. Moreover, bacteriological analysis of hens was negative. The condition was reproduced in commercial brown layers after intratracheal inoculation with virus isolates from affected flocks. It is concluded that the LPAI H6N1 virus is very likely the only cause of the disease. An overview of main manuscripts published since 1976 describing non-H5 and non-H7 avian influenza (AI) virus infections in chickens and their biological significance is included in the present study, in which once more is shown that not only high pathogenic AI virus subtypes H5 and H7 can be detrimental to flocks of productive layers, but also non-H5 and non-H7 LPAI viruses (H6N1 virus). RESEARCH HIGHLIGHTS LPAI H6N1 can be detrimental to productive layers Detrimental effects are severe egg drop and persistent high mortality LPAI H6N1 virus outbreak seems to be self-limiting.
在两个月内，荷兰三个农场的四个产蛋褐壳蛋鸡群爆发了低致病性禽流感（LPAI）H6N1亚型感染（静脉内致病性指数=0.11）。这些农场彼此之间的最大距离为4.6公里。感染与产蛋量下降高达74%、蛋壳颜色变浅以及持续的高死亡率（每周高达3.2%）有关。三个鸡群因不再盈利而被提前宰杀。新城疫、传染性支气管炎、产蛋下降综合征和鸡毒支原体感染很可能被排除为该疾病在现场的病因或促成因素。此外，在受影响鸡群的鸡蛋中未检测到可导致产蛋量下降和蛋壳褪色的抗球虫药物尼卡巴嗪。此外，尸检未发现表明细菌感染的病变。而且，母鸡的细菌学分析结果为阴性。用来自受影响鸡群的病毒分离株进行气管内接种后，在商业褐壳蛋鸡中再现了这种病症。得出的结论是，LPAI H6N1病毒很可能是该疾病的唯一病因。本研究包括了自1976年以来发表的描述鸡非H5和非H7禽流感（AI）病毒感染及其生物学意义的主要手稿概述，其中再次表明，不仅高致病性AI病毒亚型H5和H7会对产蛋鸡群有害，非H5和非H7 LPAI病毒（H6N1病毒）也会如此。研究亮点：LPAI H6N1会对产蛋鸡群有害；有害影响包括严重的产蛋下降和持续的高死亡率；LPAI H6N1病毒爆发似乎具有自限性。
