الفهرس 
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Abstract
Clade 2.3.4.4 of highly pathogenic avian influenza (HPAI) H5N8 virus was first emerged in China. The virus disseminated throughout migrating birds into different countries in Asia, America, Europe and Africa. HPAI A/H5N8 viruses were initially reported in Egypt in winter of 2016. However, backyard poultry production sector is commonly found in rural areas in Egypt with biosecurity limitations and could play a significant role in the epidemiology of AIVs in Egypt. As a resul, the purpose of our research was to determine the prevalence of AIVs in backyard Ducks and geese in Assuit governorate, Egypt during 2018, and to study the genetic features of detected AIVs. A total of 245 oropharyngeal and cloacal swabs were collected from backyard waterfowls (ducks ≈ 92 and geese ≈ 32) either apparent healthy or demonstrated severe clinical signs of AIV infection from 5 different sites. AIVs were successfully isolated in SPF-ECE from 50 swabs collected from both waterfowls. All isolates were subtyped as H5N8 viruses. H5N1 and H9N2 subtypes were not identified among collected samples.
Two representative H5N8 isolates from duck and goose were subjected to full genome sequencing and genetic analysis. Although both of H5N8 viruses were closely related to clade 2.3.4.4b, they were genetically distinct and had genetically different constellation forms. This study highlights the need of active surveillance of AIVs in backyard production sector for assessing the epidemiology, evolution, and diversity of currently circulating viruses in Egypt.