Emergence of Highly Pathogenic Avian Influenza A Virus (H5N1) of Clade 2.3.4.4b in Egypt, 2021–2022

Abstract

Wild migratory birds have the capability to spread avian influenza virus (AIV) over long distances as well as transmit the virus to domestic birds. In this study, swab and tissue samples were obtained from 190 migratory birds during close surveillance in Egypt in response to the recent outbreaks of the highly pathogenic avian influenza (HPAI) H5N1 virus. The collected samples were tested for a variety of AIV subtypes (H5N1, H9N2, H5N8, and H6N2) as well as other pathogens such as NDV, IBV, ILT, IBDV, and WNV. Among all of the tested samples, the HPAI H5N1 virus was found in six samples; the other samples were found to be negative for all of the tested pathogens. The Egyptian HPAI H5N1 strains shared genetic traits with the HPAI H5N1 strains that are currently being reported in Europe, North America, Asia, and Africa in 2021–2022. Whole genome sequencing revealed markers associated with mammalian adaption and virulence traits among different gene segments, similar to those found in HPAI H5N1 strains detected in Europe and Africa. The detection of the HPAI H5N1 strain of clade 2.3.4.4b in wild birds in Egypt underlines the risk of the introduction of this strain into the local poultry population. Hence, there is reason to be vigilant and continue epidemiological and molecular monitoring of the AIV in close proximity to the domestic–wild bird interface.

Epidemiology and phylodynamics of multiple clades of H5N1 circulating in domestic duck farms in different production systems in Bangladesh

“…So, it might be possible that migratory birds of the Central Asian flyway may influence the transmission of this novel clade in Bangladesh. Though the H5N1 viruses with clade 2.3.4.4b have only been detected in Ducks in Bangladesh, this clade has been detected in wild birds and domestic Anseriformes and Galliformes in other countries ( 83–85 ). On the other hand, this clade has also caused outbreaks in minks in Spain ( 86 ).…”

Immunogenicity and Cross-Protective Efficacy Induced by an Inactivated Recombinant Avian Influenza A/H5N1 (Clade 2.3.4.4b) Vaccine against Co-Circulating Influenza A/H5Nx Viruses

“…Being a bridge between the three old world continents, Europe, Asia and Africa, where internationally important migration routes for birds intersect, enabling the migrating birds to disseminate new viruses to the Egyptian environment; by 2017, the predefined H5N1 variants were gradually replaced with the HPAIV H5N8 of clade 2.3.4.4 that emerged in Egypt in 2016 [ 33 ]. In late 2021, the newly emerging H5N1 of clade 2.3.4.4 has been introduced to Egypt via migratory birds and is currently cocirculating with the HPAIV H5N8 of clade 2.3.4.4 [ 5 ]. Due to the endemic situation of avian influenza viruses, the control strategy of avian influenza in Egypt recommends the application of inactivated vaccines that match genetically and antigenically to the circulating strains [ 34 , 35 ].…”

“…Since late 2020, outbreaks of highly pathogenic avian influenza (HPAI) H5N1 virus (clade 2.3.4.4b) continue to be reported around the world in both wild birds and, on several occasions, domestic poultry, with substantial genetic evolution and reassortment, enabling the emergence of several variants [ 1 , 2 , 3 , 4 ]. In late 2021, the HPAI H5N1 virus was found in migratory birds in Egypt with some cases in domestic poultry in early 2022 [ 5 ].…”

Appraisal of Three Commercial Inactivated Avian Influenza Vaccines Efficacy Against Challenge with Egyptian Duck-Origin Clade 2.3.4.4b H5N8 in Commercial Broiler Chickens

“…During 2021, the HPAI H5N8 virus was reported for the first time in humans who have a history of contact with infected poultry in Russia (WHO, 2021). Moreover, HPAI (H5N1) and (H5N5) belonging to clade 2.3.4.4b has been detected recently in Egypt at migratory birds (Mosaad et al, 2023& Kandeil et al, 2023 which may lead to further complication of AI disease situation in Egypt. The controlling of AI infections in Egypt depends mainly on vaccination as a routine control strategy to minimize losses in poultry production by limiting the spread of infection.…”