Zoonotic Potential and Risk Factors Associated with Avian Influenza H5N1 Infection in Poultry and Their Handlers in Egypt

Abstract

In recent years, public health concerns have arisen due to the high pathogenicity of the avian influenza A (H5N1) virus, especially in South-East Asia and Egypt. Birds living in an aquatic habitat are naturally affected by avian influenza virus (AIV). Also the virus can infect domestic poultry, pet birds, other animal species, and occasionally also infecting humans (WHO, 2015). The AIVs typically cause subclinical infection in domestic poultry including chickens, ducks, goose, and turkeys, while some strains can lead to a high mortality rate (Abou El-Amaiem et al., 2013). However, cases of human infection with AI have been reported, transmission from human to human rarely occurred b(CDC 2017 ). AIVs belong to type A influenza genus, family Orthomyxoviridae. An influenza a virus is an enveloped, eight segmented RNA virus, the genome is negative-sense, single-stranded and belongs to the Orthomyxoviridae family. Viruses of Type A (and B) cause nearly every year recurrent epidemics, causing significant human mortality and morbidity (Malik Peiris et al., 2007) Eighteen haemagglutinin HA (H1-H18) and eleven neuraminidase NA (N1-N11) subtypes are well-known for influenza viruses A (ICTV, 2017). It is usually difficult if not impossible for different types of HA or NA to cross-protect one another, and these functions are essential for the immune response. The high variability is the result of mutation and genetic reassortment (OIE, 2015), by going through antigenic drift or shift, respectively. The antigenic drift represents the small changes that happen continually over time as the virus replicates, and usually result in new strain variants that are closely related. However, the antigenic shift denotes either major changes in the virus, or re-assortment between avian and human influenza strains, or between avian and other animal influenza strains which results in a new influenza A subtype (Wimmer et al., 2010). Among the HP AIVs, H5N1 subtype represents a great concern particularly in South-East Asia and in Egypt (Fasanmi et al., 2017). This is attributed to the massive mortality caused by H5N1 in the domestic poultry, the unusual high virulence in wild birds, and the ability to infect humans (Haider et al., 2017), few cases of