A brief summary of the epidemiology and genetic relatedness of avian influenza H9N2 virus in birds and mammals in the Middle East and North Africa

Abstract

H9N2 is the most widespread avian influenza virus subtype in poultry worldwide. It infects a broad spectrum of host species including birds and mammals. Infections in poultry and humans vary from silent to fatal. Importantly, all AIV, which are fatal in humans (e.g. H5N1, H7N9) acquired their 'internal' gene segments from H9N2 viruses. Although H9N2 is endemic in the Middle East (ME) and North Africa since the late 1990s, little is known about its epidemiology and genetics on a regional level. In this review, we summarised the epidemiological situation of H9N2 in poultry and mammals in Iran, Iraq, Kuwait, Qatar, United Arab Emirates, Oman, Bahrain, Yemen, Saudi Arabia, Jordan, Palestine, Israel, Syria, Lebanon, Turkey, Egypt, Sudan, Libya, Tunisia, Algeria and Morocco. The virus has been isolated from humans in Egypt and serosurveys indicated widespread infection particularly among poultry workers and pigs in some countries. Some isolates replicated well in experimentally inoculated dogs, mice, hamsters and ferrets. Insufficient protection of immunised poultry was frequently reported most likely due to concurrent viral or bacterial infections and antigenic drift of the field viruses from outdated vaccine strains. Genetic analysis indicated several distinct phylogroups including a panzootic genotype in the Asian and African parts of the ME, which may be useful for the development of vaccines. The extensive circulation of H9N2 for about 20 years in this region where the H5N1 virus is also endemic in some countries, poses a serious public health threat. Regional surveillance and control strategy are highly recommended.

A(H9N2) influenza viruses associated with chicken mortality in outbreaks in Algeria 2017

“…Although considerable genotypic heterogeneity is present, the HA genes from the A(H9N2) viruses most frequently isolated from gallinaceous poultry fall into three dominant genetic groups represented by A/quail/Hong Kong/G1/97 (G1 lineage), A/chicken/Hong Kong/Y280/97 (Y280 lineage), and A/chicken/Beijing/1/94 (Ck/Bei lineage) . While the geographic range of the Y280 and Ck/Bei lineages has remained relatively confined, viruses of the G1 lineage spread from Southeast Asia to the Indian subcontinent in the late 1990s, through the Middle East soon after, and more recently into Northern Africa . In Africa, widespread reports of A(H9N2) viruses in Egypt began in 2011, although other studies suggested that the virus was likely present earlier and quickly became endemic cocirculating with A(H5N1) viruses .…”

“…While the geographic range of the Y280 and Ck/Bei lineages has remained relatively confined, viruses of the G1 lineage spread from Southeast Asia to the Indian subcontinent in the late 1990s, through the Middle East soon after, and more recently into Northern Africa . In Africa, widespread reports of A(H9N2) viruses in Egypt began in 2011, although other studies suggested that the virus was likely present earlier and quickly became endemic cocirculating with A(H5N1) viruses . It appeared that a similar time frame likely existed for A(H9N2) viruses in Libya and Tunisia, although lack of longitudinal regular surveillance, as was implemented in Egypt, makes it difficult to determine the full impact of these viruses in these countries.…”

“…In Africa, widespread reports of A(H9N2) viruses in Egypt began in 2011, although other studies suggested that the virus was likely present earlier and quickly became endemic cocirculating with A(H5N1) viruses . It appeared that a similar time frame likely existed for A(H9N2) viruses in Libya and Tunisia, although lack of longitudinal regular surveillance, as was implemented in Egypt, makes it difficult to determine the full impact of these viruses in these countries. Further, A(H9N2) viruses were detected in chickens in Morocco in 2016 …”

Human‐infecting influenza A (H9N2) virus: A forgotten potential pandemic strain?

“…Avian H9N2 subtype influenza A virus was prevalent in its natural reservoir, wild waterfowls (Nagy, Mettenleiter, & Abdelwhab, ; Pusch, & Suarez, ). Since the first detection in China in early 1990, it became widely spread in land‐based poultry crossing mainland China (Li et al, ).…”

“…Such enlarged host range of H9N2 viruses suggested that it gained the capability for overcoming host restriction factors. In addition to Southeast Asian countries, avian H9N2 virus was also enzootic in poultry in Middle Eastern and North African countries (Kandeil et al, ; Nagy et al, ).…”