Laleye Agnes Tinuke, Bianco Alice, Shittu Ismaila, Sulaiman Lanre, Fusaro Alice, Inuwa Bitrus, Oyetunde Joshua, Zecchin Bianca, Bakam Judith, Pastori Ambra, Olawuyi Kayode, Schivo Alessia, Meseko Clement, Vakuru Columba, Fortin Andrea, Monne Isabella, Joannis Tony
National Veterinary Research Institute, Vom, Nigeria.
Istituto Zooprofilattico Sperimentale delle Venezie, Padova, Italy.
Transbound Emerg Dis. 2022 Mar;69(2):423-433. doi: 10.1111/tbed.14000. Epub 2021 Feb 7.
Among recurrent sanitary emergencies able to spread rapidly worldwide, avian influenza is one of the main constraints for animal health and food security. In West Africa, Nigeria has been experiencing repeated outbreaks of different strains of avian influenza virus (AIV) since 2006 and is also recognized as a hot spot in the region for the introduction of emerging strains by migratory wild birds. Here, we generated complete genomes of 20 highly pathogenic avian influenza (HPAI) H5N8 viruses collected during active surveillance in Nigerian live bird markets (LBM) and from outbreaks reported in the country between 2016 and 2019. Phylogenetic analysis reveals that the Nigerian viruses cluster into four separate genetic groups within HPAI H5 clade 2.3.4.4b. The first group includes 2016-2017 Nigerian viruses with high genetic similarity to H5N8 viruses detected in Central African countries, while the second includes Nigerian viruses collected both in LBM and poultry farms (2018-2019), as well as in Cameroon, Egypt and Siberia. A natural reassortant strain identified in 2019 represents the third group: H5N8 viruses with the same gene constellation were identified in 2018 in South Africa. Finally, the fourth introduction represents the first detection in the African continent of the H5N6 subtype, which is related to European viruses. Bayesian phylogeographic analyses confirmed that the four introductions originated from different sources and provide evidence of the virus spread within Nigeria, as well as diffusion beyond its borders. The multiple epidemiological links between Nigeria, Central and Southern African countries highlight the need for harmonized and coordinated surveillance system to control AIV impact. Improved surveillance at the Wetlands, LBMs and early warning of outbreaks are crucial for prevention and control of AIV, which can be potentially zoonotic and be a threat to human health.
在能够在全球迅速传播的反复出现的卫生紧急情况中，禽流感是动物健康和粮食安全的主要制约因素之一。在西非，自2006年以来，尼日利亚一直经历不同毒株的禽流感病毒（AIV）反复爆发，该国也被认为是该地区候鸟引入新出现毒株的热点地区。在此，我们生成了20株高致病性禽流感（HPAI）H5N8病毒的完整基因组，这些病毒是在尼日利亚活禽市场（LBM）的主动监测期间以及2016年至2019年该国报告的疫情中收集的。系统发育分析表明，尼日利亚病毒在HPAI H5进化枝2.3.4.4b内聚为四个独立的遗传组。第一组包括2016 - 2017年尼日利亚病毒，与在中非国家检测到的H5N8病毒具有高度遗传相似性，而第二组包括在LBM和家禽养殖场收集的尼日利亚病毒（2018 - 2019年），以及在喀麦隆、埃及和西伯利亚收集的病毒。2019年鉴定出的一种自然重配毒株代表第三组：2018年在南非鉴定出具有相同基因组合的H5N8病毒。最后，第四次引入代表在非洲大陆首次检测到H5N6亚型，它与欧洲病毒有关。贝叶斯系统发育地理学分析证实，这四次引入源自不同来源，并提供了病毒在尼日利亚境内传播以及扩散到其边界之外的证据。尼日利亚与中非和南非国家之间的多重流行病学联系凸显了建立统一协调监测系统以控制禽流感病毒影响的必要性。改善湿地、活禽市场的监测以及疫情早期预警对于预防和控制禽流感病毒至关重要，因为禽流感病毒可能是人畜共患病，对人类健康构成威胁。
