Evolution and Spread of Avian Influenza H5N1 Viruses

Abstract

The Asian lineage of H5N1 avian influenza virus emerged from geese (A/Goose/Guangdong/1/96) in China in 1996, and is continuing its spread infecting domestic poultry, other birds and sporadic infection to humans revealing its pandemic potential. Since late 2003, H5N1 virus has been reported over 60 counties in Asia, Europe and Africa killing millions of poultry and infected humans in 16 countries with a total of 650 confirmed cases including 386 fatal have been reported to WHO. Spread of H5N1 virus has been linked with bird migration, although trade of poultry and poultry products has also been attributed in the spread. During the last one and half decades of circulation in poultry, the H5N1 virus has undergone significant genetic diversification leading to emergence of 10 major virus clades (clades 0-9), with subsequent diversification into 2nd-, 3rd-and 4th-order clades. Vaccination is one of the strategies for control and prevention of H5N1 virus infection; however, some countries still face challenges to eliminate H5N1 virus in poultry. One of the major problems is antigenic drift in viruses that develops due to vaccine pressure, particularly when vaccination is not implemented properly. Two classes of anti-viral drugs (neuraminidase inhibitors and adamantanes) are available for treatment and prophylaxis of influenza; however, there is emergence of drug resistant variants in poultry and humans. Widespread circulation and ever changing nature of H5N1 virus make avian influenza control program more difficult. Therefore, educational programs to enhance awareness on avian influenza, animal husbandry practices and biosecurity measures are important in control of the disease. All copyrights reserved to Nexus® academic publishers

Lineage‐specific epitope profiles for HPAI H5 pre‐pandemic vaccine selection and evaluation

“…Even though human infection with HPAI H5 is relatively rare, when it does occur, the case fatality rate is high. From 2003 to 2014, 667 human cases have been identified, of which 58.9% were fatal . Although there is no evidence of sustained human‐to‐human transmission, the rapid emergence of novel strains of H5 viruses from animal reservoirs combined with the sporadic human infections indicates a high risk for pandemic HPAI H5 emergence.…”

“…From 2003 to 2014, 667 human cases have been identified, of which 58.9% were fatal. 13 Although there is no evidence of sustained human-to-human transmission, the rapid emergence of novel strains of H5 viruses from animal reservoirs combined with the sporadic human infections indicates a high risk for pandemic HPAI H5 emergence. Two recent studies independently demonstrated that as few as three to five mutations in HPAI H5N1 viruses could allow for the effective aerosol transmission between ferrets.…”

Genomic epidemiology of highly pathogenic avian influenza A (H5N1) virus in wild birds in South Korea during 2021–2022: Changes in viral epidemic patterns

“…Remarkably, long-distance transmission of some Gs/GD lineage H5Nx viruses by migratory birds had resulted in global HPAI outbreaks. A large outbreak of clade 2.2 H5N1 virus occurred in migratory waterfowl at Qinghai Lake, China, in 2005 and subsequently spread across Asia and into Europe ( Tosh et al. 2014 ).…”

Clade-level Spatial Modelling of HPAI H5N1 Dynamics in the Mekong Region Reveals New Patterns and Associations with Agro-Ecological Factors

“…Over the period 2004–2014, the virus was introduced in more than 60 countries and in almost all cases, the virus did not persist. However, due to specific conditions in poultry production and value chain systems, and/or limited veterinary resources, the disease has remained endemic or recurrent in China, Viet Nam, Indonesia, Egypt, Bangladesh and Nepal 3 4 .…”