Avian influenza viruses at the wild–domestic bird interface in Egypt

Abstract

Wild birds of the orders Anseriforme s (mainly ducks, geese and swans) and Charadriiformes (mainly gulls, terns and waders) constitute the natural reservoir for low pathogenic avian influenza (LPAI) viruses. In Egypt, highly pathogenic avian influenza (HPAI) H5N1 and LPAI H9N2 viruses are endemic in domestic poultry, forming a threat to animal and human health and raising questions about the routes of introduction and mechanisms of persistence. Recently, HPAI H5N8 virus was also introduced into Egyptian domestic birds. Here we review the literature on the role of wild birds in the introduction and endemicity of avian influenza viruses in Egypt. Dabbling ducks in Egypt harbor an extensive LPAI virus diversity and may constitute the route of introduction for HPAI H5N1 and HPAI H5N8 viruses into Egypt through migration, however their role in the endemicity of HPAI H5N1, LPAI H9N2 and potentially other avian influenza virus (AIV) strains – by means of reassortment of viral genes – is less clear. Strengthened surveillance programs, in both domestic and wild birds, that include all LPAI virus subtypes and full genome sequencing are needed to better assess the wild–domestic bird interface and form a basis for evidence-based measures to limit and prevent AIV transmission between wild and domestic birds.

Wild Birds in Live Birds Markets: Potential Reservoirs of Enzootic Avian Influenza Viruses and Antimicrobial Resistant Enterobacteriaceae in Northern Egypt

“…This is necessary to understand the mode of transmission of resistant bacteria and enzootic AIV to wild birds and their ability to maintain and disseminate infection into the environment. Further, the high prevalence of antibiotic-resistant bacteria and presence of diversified E. coli serotypes, Salmonella pathotypes, and AIV in some species, such as Northern shoveler, which is considered a very common migratory bird that lands in Egypt for about four months per year, highlights the importance of providing a list of the number and species of the sampled birds in all future studies [11] and strengthens the importance of the directed surveillance in particular important wild birds.…”

“…After long journeys from Europe and Asia, millions of exhausted wild birds rest in the wetlands of northern Egypt, especially around where the river Nile drains into the Mediterranean Sea. In this area, the trapping of wild birds is a very ancient and common practice for commercial sale in live bird markets [11]. Both residences of wild birds and offering them for sale in live bird markets represent a considerable risk for the spillover of the infection to domestic birds and possibly vice versa.…”

“…Wild migratory birds land in wetland areas in Egypt that are close to human activities including backyard and commercial farming, especially on the northern coast. These areas are where most of the cases have been confirmed [11].…”

“…Furthermore, wild birds, especially waterfowl, represent the natural reservoir for influenza A viruses (IAV), which mostly present in the low pathogenic (LPAI) forms, including the H5 and H7 subtypes that were transmitted and maintained in domestic birds, to convert to high pathogenic avian influenza (HPAI) [9,10]. However, wild birds could also be a direct source of HPAI as in the case of the introduction of H5N1 and H5N8 to Egypt [11]. The other way around has been reported in outbreaks of HPAI-H5N1 in Asia, where HPAI subtypes have spilled over into wild bird populations from domestic birds in live bird markets (LBM) [12].…”

A Systematic Review Analyzing the Prevalence and Circulation of Influenza Viruses in Swine Population Worldwide

“…Intriguingly, most of the swine samples processed in Australia, Europe, and North America were obtained from the symptomatic swine whi Egypt is recognized as a "hot spot" for the influenza virus reassortment due to its geographical location [345]. The role of migratory wild birds in the introduction of avian influenza in Egypt has been already established [346,347], and the highly pathogenic strains of the IAV have previously been detected in migratory birds in Egypt [348]. Since migratory wild birds were reported to harbor in the vicinity of Cairo [60] therefore, the probability of the migratory bird-swine interaction in the regions remain high which very well explains the occurrence of highly and low pathogenic strains of avianorigin IAV in swine in Cairo, Egypt.…”