![]() ![]() ![]() The number of poultry lost in the outbreaks that occurred before 2004 is not available however, between January 2005 and November 2022, H5 highly pathogenic avian influenza viruses have caused 8534 outbreaks and the loss of 389 million poultry around the world ( Figure 1(a)), according to the information reported in the OIE-World Animal Health Information System (OIE-WAHIS, ). ![]() In 20, avian influenza outbreaks caused by H5N1 viruses were reported in several Asian countries, including Vietnam, Thailand, Indonesia, China, Japan, South Korea, Cambodia, and Lao. In this century, the first H5 avian influenza outbreak occurred in Hong Kong in 2002, caused by an H5N1 virus. The first recorded highly pathogenic avian influenza outbreak was caused by H5N1 virus in chickens in Scotland in 1959 in 1966, an avian influenza outbreak in turkeys in Canada was caused by H5N9 virus an H5N2 virus caused multiple outbreaks in chickens and turkeys in the US from 1983 to 1985 in 1983, an H5N8 virus caused disease outbreaks in turkeys, chickens, and ducks in Ireland in 1991, an H5N1 virus caused a disease outbreak in turkeys in England an H5N2 virus caused multiple outbreaks in chickens and turkeys in Mexico from 1994 to 1995 and in 1997, an H5N1 virus and an H5N2 virus caused outbreaks in chickens in Hong Kong and Italy, respectively. In the last century, avian influenza outbreaks caused by different H5 viruses have occurred in eight countries or regions. In this review, we briefly summarize the H5 and H7 influenza outbreaks and the damage they have caused to the global poultry industry and public health, analyze the evolution and spread of H5 viruses, and discuss the effectiveness of the poultry vaccination strategy for highly pathogenic avian influenza control.Īvian influenza outbreaks caused by H5 viruses Some strains bearing the HA gene of the H5 or H7 subtypes are highly pathogenic for poultry and have caused severe problems for the global poultry industry. Although different subtypes of viruses have been detected in domestic poultry, especially waterfowl that come into close contact with wild birds, only three HA subtypes-H5, H7, and H9-have spread and been detected in domestic poultry across wide geographic areas. The avian influenza viruses are maintained and circulate in wild birds. Viruses of several other subtypes that circulate in animals have also jumped to humans on multiple occasions, and some of them have shown pandemic potential. H1N1, H2N2, and H3N2 viruses have caused four influenza pandemics since 1918, and H1N1 and H3N2 viruses continue to co-circulate in humans globally. Currently, 16 HA subtypes and nine NA subtypes have been detected in avian species. On the basis of the antigenicity of the HA and NA proteins, influenza viruses are divided into different subtypes. Each of these segments encodes one to three proteins. The genome of influenza A virus comprises eight gene segments: basic polymerase 2 (PB2), basic polymerase 1 (PB1), acidic polymerase (PA), hemagglutinin (HA), nucleoprotein (NP), neuraminidase (NA), matrix (M), and nonstructural protein (NS). Influenza A viruses are important pathogens that continually challenge both human and animal health. ![]() Given that the H5N1 viruses are widely circulating in wild birds and causing problems in domestic poultry around the world, we recommend that any unnecessary obstacles to vaccination strategies should be removed immediately and forever. In this review, we briefly summarize the damages the H5 and H7 influenza viruses have caused to the global poultry industry and public health, analyze the origin, evolution, and spread of the H5 viruses that caused the waves, and discuss how and why the vaccination strategy in China has been a success. As the largest poultry-producing country in the world, China lost relatively few poultry during the three waves of global H5 avian influenza outbreaks, and nearly eliminated the pervasive H7N9 viruses that emerged in 2013. Many countries in Europe and North America control highly pathogenic avian influenza by culling alone, whereas some countries, including China, have adopted a “cull plus vaccination” strategy. The H5 influenza viruses are spread by migratory wild birds and have caused three waves of influenza outbreaks across multiple continents, and the third wave that started in 2020 is ongoing. These viruses have caused numerous disease outbreaks in wild birds and domestic poultry, and are responsible for the loss of at least 422 million domestic birds since 2005. Viruses bearing the hemagglutinin (HA) gene of the H5 subtype and H7 subtype have caused 2634 human cases around the world, including more than 1000 deaths. Avian influenza viruses continue to present challenges to animal and human health. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |