Epidemiological Findings of Outbreaks of Disease Caused by Highly Pathogenic H5N1 Avian Influenza Virus in Poultry in Egypt During 2006

Abstract

This paper describes the first threats of H5N1 avian influenza outbreaks in Egypt recorded from February to December 2006 in commercial and domestic poultry from different species and summarizes the major characteristics of the outbreak. There were 1024 cases from different poultry species (rural and commercial chickens of different breeding types, turkeys, ducks, geese, and quail) either in commercial breeding or in backyards from different locations in Egypt. All tested positive for the H5N1 subtype. From these cases only 12 avian influenza A viruses were isolated and characterized from samples collected during outbreaks. All isolates were characterized, and the data confirmed that the isolated viruses belong to highly pathogenic avian influenza of subtype H5N1. Full hemagglutinin (HA) gene (segment 4) sequencing was also done, and the sequences of these isolates were compared with other strains from Russia, Africa, and the Middle East. The data revealed that all Egyptian strains were very closely related and belonging to subclade 2.2 of the H5N1 virus of Eurasian origin, the same one circulating in the Middle East region and introduced into Africa at the beginning of 2006. This study showed evidence of the wide spread of H5N1 virus infection in domestic poultry in Egypt within a short time. The most obvious features of these outbreaks were severe clinical signs and high mortalities as well as very rapid and widespread occurrence within the country in a very short time. The possible causes of its rapid spread and prospects of disease control are discussed.

Distribution of avian influenza H5N1 viral RNA in tissues of AI-vaccinated and unvaccinated contact chickens after experimental infection

“…Since 2006, infection with HPAIV subtype H5N1 of clade 2.2.1 has resulted in the culling of hundreds of millions of birds and has disrupted food security in Egypt [6]. The poultry industry has embarked on a mass vaccination policy to reduce circulation of the H5N1 virus, but with limited success [4].…”

Evolution of highly pathogenic avian influenza H5N1 viruses in Egypt indicating progressive adaptation

“…HPAI virus of subtype H5N1 was first recognized in Egypt in 2006 [3], and since then, the disease has become endemic and still causes a significant threat to the poultry industry and humans in Egypt. Village poultry and household birds constitute one large sector of poultry production in Egypt, with approximately 4-5 million families who are closely associated with their birds, estimated at 250 million birds.…”

Protective efficacy of a prime-boost protocol using H5-DNA plasmid as prime and inactivated H5N2 vaccine as the booster against the Egyptian avian influenza challenge virus

“…The selection of Mexican inactivated H5N2 vaccine was based on the fact that it was one of the first vaccines used to combat clade 2.2 HPAI in Egypt since its introduction in 2006 (Aly et al, 2008). Following emergence of the variant HPAI 2.2.1.1 H5N1 viruses in Egypt in 2007, failure of Mexican H5N2-based vaccines to confer either clinical protection or to decrease virus shedding due to strain heterogeneity was reported (Abdelwhab et al, 2011;Hassan et al, 2012).…”

“…The viral genome encodes at least 10 proteins . Disease caused by the highly pathogenic avian influenza (HPAI) H5N1 virus has been endemic in Egypt since 2008, after the first cases were reported in 2006 (Aly et al, 2008). The disease has caused massive economic losses in the poultry industry, directly by ravaging the poultry population and indirectly by forcing approximately 1.5 million people working in this industry to lose their main source of livelihood (Abdelwhab et al, 2010).…”