In December 2018, suspected outbreaks of equine influenza (EI) were observed in donkeys in Sokoto State, in the extreme northwest of Nigeria bordering the Republic of the Niger. Equine influenza virus (EIV) subtype H3N8 was the etiologic agent identified in the outbreaks using real-time RT-qPCR and sequencing of both the partial haemagglutinin (HA) gene and the complete genome. Since then the H3N8 virus spread to 7 of the 19 northern states of Nigeria, where it affected both donkeys and horses. Phylogenetic analysis of the partial and complete HA gene revealed the closest nucleotide similarity (99.7%) with EIVs belonging to the Florida clade 1 (Fc-1) of the American lineage isolated in 2018 from Argentina and Chile. In total, 80 amino acid substitutions were observed in the viral proteins when compared to the OIE-recommended Fc-1 vaccine strains. The HA and neuraminidase proteins respectively had 13 and 16 amino acid substitutions. This study represents the first reported outbreak of EI caused by an Fc-1 virus in Nigeria and in the West Africa sub-region. Based on this report, extensive disease surveillance in equids is required to establish the circulating lineages and design an effective control strategy to protect the considerable population of horses and donkeys in the country.

2018年12月，在与尼日尔共和国接壤的尼日利亚最西北端的索科托州的驴子中发现了疑似马流感（EI）暴发。马流感病毒（EIV）H3N8亚型是在暴发中使用实时RT-qPCR以及部分血凝素（HA）基因和完整基因组测序的病原体。此后，H3N8病毒扩散到尼日利亚19个北部州中的7个州，在此同时影响了驴和马。对部分和完整HA基因的系统进化分析显示，与2018年从阿根廷和智利分离出的美国谱系的佛罗里达进化枝1（Fc-1）的EIV具有最接近的核苷酸相似性（99.7％）。与OIE推荐的Fc-1疫苗株相比，在病毒蛋白中总共观察到80个氨基酸取代。HA和神经氨酸酶蛋白分别具有13和16个氨基酸取代。这项研究代表了尼日利亚和西非次区域首次报道的由Fc-1病毒引起的EI爆发。根据此报告，需要对马匹进行全面的疾病监视以建立流行血统并设计有效的控制策略，以保护该国大量的马和驴。