Highly pathogenic avian influenza H5N1 was detected for the first time in Nigeria and Africa in 2006. The source of the outbreak was not immediately clear, but scientific opinions favoured multiple introductions. The need to evaluate available epidemiological and virological data to demonstrate most probable source of introduction is important for focused control efforts. In this study, we described ten years (2006-2016) scientific observations available through ecology, epidemio-surveillance and molecular virology of avian influenza in Nigeria. Nigeria is geographically located in the tropical humid region with abundant wetlands presenting ideal ambience for birdlife. Ornithological evidence also showed that the country lies in the path of two major migratory flyways from Europe and Asia providing opportunities for co-mingling of different species and age of wild birds with resident birds. Genomic characterization including phylogenetic analysis revealed a high degree of homology among virus strains isolated in Nigeria and those detected in migratory birds from Europe suggesting common source epidemic. This study agreed with postulation that migratory wild birds from Europe may be responsible for the introduction of highly pathogenic avian influenza subtype H5N1 to Nigeria. Feral waterfowls around water bodies thereafter bridge transmission to domestic poultry holdings whereas local trade and movement of poultry and poultry products may further spread infection locally. In the light of this understanding, routine risk based sentinel surveillance for avian influenza in domestic waterfowls in ecological hotspots is recommended for early detection and response thereby saving economic losses and mitigating public health emergencies.
Key words: Avian influenza, Migratory waterfowls, Nigeria, Poultry
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