ABSTRACT
Since November 2018, several countries in West and Central Africa have reported mortalities in donkeys and horses. Specifically, more than 66,000 horses and donkeys have succumbed to disease in Burkina Faso, Chad, Cameroon, The Gambia, Ghana, Mali, Niger, Nigeria, and Senegal. Strangles caused by Streptococcus equi subsp equi, African Horse Sickness (AHS) virus, and Equine influenza virus (EIV) were all suspected as potential causative agents. This study reports the identification of EIV in field samples collected in Niger and Senegal. Phylogenetic analysis of the hemagglutinin and neuraminidase genes revealed that the identified viruses belonged to clade 1 of the Florida sublineage and were very similar to viruses identified in Nigeria in 2019. Interestingly, they were also more similar to EIVs from recent outbreaks in South America than to those in Europe and the USA. This is one of the first reports providing detailed description and characterization of EIVs in West and Central Africa region.
Subject(s)
Disease Outbreaks/veterinary , Horse Diseases/epidemiology , Influenza A Virus, H3N8 Subtype/genetics , Orthomyxoviridae Infections/veterinary , Animals , Genes, Viral , Hemagglutinin Glycoproteins, Influenza Virus/genetics , Horse Diseases/transmission , Horse Diseases/virology , Horses , Influenza A Virus, H3N8 Subtype/classification , Neuraminidase/genetics , Niger/epidemiology , Orthomyxoviridae Infections/epidemiology , Orthomyxoviridae Infections/transmission , Orthomyxoviridae Infections/virology , Phylogeny , Senegal/epidemiologyABSTRACT
The role of Africa in the dynamics of the global spread of a zoonotic and economically-important virus, such as the highly pathogenic avian influenza (HPAI) H5Nx of the Gs/GD lineage, remains unexplored. Here we characterise the spatiotemporal patterns of virus diffusion during three HPAI H5Nx intercontinental epidemic waves and demonstrate that Africa mainly acted as an ecological sink of the HPAI H5Nx viruses. A joint analysis of host dynamics and continuous spatial diffusion indicates that poultry trade as well as wild bird migrations have contributed to the virus spreading into Africa, with West Africa acting as a crucial hotspot for virus introduction and dissemination into the continent. We demonstrate varying paths of avian influenza incursions into Africa as well as virus spread within Africa over time, which reveal that virus expansion is a complex phenomenon, shaped by an intricate interplay between avian host ecology, virus characteristics and environmental variables.
