Migratory Birds as Disseminators of Avian Influenza Viruses to Egypt (2003 – 2023)

Abstract

Migratory birds are considered a vessel for preserving and transmitting microbes, which contribute with great force in transporting them from one place to another over long distances in the world. This would contribute to the emergence of disease pandemics globally and the most obvious example is the avian influenza (AI) epidemics over time. The most famous recent scenario is the AI pandemic that began in Hong Kong in 1990s. Natural resistance to AI helps migratory birds retain avian influenza viruses (AIVs) for long periods and transfer them from their source to many other countries during migration paths. Accordingly, they serve as a vector for the maintenance and introduction of both highly pathogenic and low pathogenic avian influenza (HPAI and LPAI). Through this study, the subtypes of high- and low-pathogenic avian influenza viruses found in migratory and wild birds in Egypt were identified, and the most important species of implicated birds were recognized since 1970s tell now. In the view of geoepidemiology of AIVs transmitted by migratory birds, we highlighted the main entry, gathering places and movement routes encountered either with free-living or domesticated birds. By reviewing the outcomes of previous studies over the past two decades, a total of 108 AIVs including 70 of the LPAI and 38 of the HPAI were isolated from migratory and free-living birds. Migratory birds topped the list with 91% of the LPAI and 79% of the HPAI. Interestingly, Damietta province had the highest rates of virus isolation; 81.3% and 40% for LPAI and HPAI viruses respectively, followed by Sharkia particularly in HPAIV (26.7) and both borders are with Lake Manzala. Two Anseriformes-migratory birds; Northern shoveler & Green-winged teal harbored more than 50% of the isolated AIVs. Therefore, we call for conducting annual screening of AIVs in spring and fall. Focusing on Anseriformes and recently proposed quails as vessels for AIVs’ mutations mainly in northeast Lakes’ border provinces for early detection and quick intervene and avoid their spread became an urgent need.