Abstract
BACKGROUND: Avian influenza viruses are still causing major concern not only to the poultry industry but also to human health across the globe. The live poultry markets and the small-scale local breeding of various species of birds in backyards are still playing important roles in the sustainability of most virulent influenza viruses, especially H5N8. METHODS: The authors investigated an outbreak of highly pathogenic avian influenza H5N8 in backyard flocks in Al Ahsa, Eastern Saudi Arabia that occurred in 2017-2018. RESULTS: A range of poultry including chickens, ostriches, ducks, pigeons and turkeys were clinically affected. Phylogenetic analysis suggested that this was a common source outbreak caused by a virus closely related to H5N8 viruses causing outbreaks elsewhere in Saudi Arabia in early 2018. CONCLUSIONS: Small backyard flocks are still contributing to the epidemiology and transmission of H5N8.