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High pathogenicity avian influenza has a significant negative impact on poultry farming, international trade and health of wild bird populations, therefore the infection requires the utmost attention of the entire international community. The article investigates the evolutionary and epidemic processes observed in recent years in many countries of the world where avian influenza outbreaks occur; describes the ways of the infection spread; the prevalence of the virus types for the last several years, as well as the expansion of the host range, including among representatives of the Mammalia class. The change in the ratio between the virus types starting from 2020, when H5N8 subtype was responsible for the overwhelming number of the disease outbreaks reported, until 2022, when an obvious predominance of H5N1 subtype was detected is demonstrated. A noticeable expansion of the disease-affected areas in Central and South America, the influence of migration, anthropogenic and other factors on influenza spread are highlighted. The conditions facilitating the occurrence of the infection outbreaks affecting mammals, wild animals and livestock, zoo and companion animals are described. Cases of mammals’ infection on the North American and Eurasian continents in zoos, nature parks, backyards and fur farms, asa rule, coincide in time with the infection outbreaks in waterfowl populations. The WAHIS data were analyzed and the high ability of the virus to spillover from birds to mammals, such as martens (minks, otters, ferrets, badgers), cats (domestic cats, cougars, leopards, lynxes), pinnipeds (common seals, grey seals), bears (brown, grizzly, American black), bottlenose dolphins, skunks, foxes, opossums, raccoons was demonstrated. Changes in the habitats of both migratory birds and mammals, including due to some human economic activities, add an ecological and urban component to the complex task of the control and prevention of the epidemic, also posing a potential threat to humans.

The results of the scientific expedition to Tere Khol and Uvs Nuur Lakes in the Republic of Tyva with the purpose of active monitoring of highly dangerous diseases in wild migratory waterfowl and epidemic analysis of these biotope water areas are presented in the paper. The Uvs Nuur Lake is a kind of an indicator for avian influenza introduction to the Russian Federation, because this is the resting and nesting area for many migratory wild birds during the period of mass migrations from Central and South-East Asian countries. In the process of active monitoring the complete autopsy of bird carcasses with description of organs and systems and sampling for laboratory diagnostics were performed. Droppings (pooled samples), parts of internal organs from dead and shot birds, blood (if possible) served as biological and pathological material for testing. While sampling, species were identified using an ornithological guide. The autopsy of dead waterfowl and birds shot for diagnostic purposes demonstrated a high worm burden of nematodes and cestodes. Two samples from European herring gulls were positive for avian influenza type A virus genome and subtype H13N6 was identified in one of them. Avian paramyxovirus serotype 1 (APMV-1), the agent of Newcastle disease, was found in one sample from gulls. The lakes of the Republic of Tyva are the most significant sites for sampling of biological material from wild birds, as the primary detection of highly pathogenic avian influenza virus in this territory is a serious signal of potential further virus spread and a precursor to a probable epizooty. Notwithstanding the absence of AIV very virulent isolate detections in wild bird populations the middle term prognosis for 2020 can be designated as cautious, as the avian influenza epidemic situation is deteriorating globally, especially in the European countries, and the threat of the virus introduction to the Russian territory with migratory birds still exists.

The paper demonstrates data on global and national spread of subtype H9 low pathogenic avian influenza in poultry. Due to no need of the mandatory disease notification to the OIE, published data are used for the analysis of the infection spread. Cases of combined low pathogenic avian influenza clinical manifestation in poultry population are described. Challenges of the infection eradication are addressed. Global spread of А/Н9 virus in poultry, its rapid evolution and zoonotic potential require close attention. Since the disease signs and clinical course are similar to the ones of other avian infectious diseases (Newcastle disease, infectious laryngotracheitis, infectious bronchitis, metapneumovirus infection, mycoplasmosis, infectious coryza, etc.), the routine laboratory diagnosis should include tests for low pathogenic avian influenza thus facilitating the rapid response to the threat. Н9 virus circulation is reflected not only in the physical condition of birds and their productivity, but it also affects the live vaccines’ efficacy during scheduled immunizations through the reduction of their protective effect and increase of post-vaccination reactions. In spite of the availability of specific prevention, the opinions of the researchers divided between its opponents and proponents. On the one hand, the vaccination eliminates the economic loses and the virus escape into the environment, but on the other hand, it can aid to “silent” spread of the virus and its established variation that is typical in case of low strength of the poultry population immunity.

The paper presents the results of analysis of epidemic situation on infectious animal diseases subject to compulsory OIE notification: FMD, African swine fever, classical swine fever, lumpy skin disease, sheep and goat pox, and highly pathogenic avian influenza. The paper presents data on the specified diseases situation in the Russian Federation, broken down by Subjects, and also provides a comparative description of the data for 2017 and 2018. Besides, attention is focused on some features of the epidemic process, depending on the season. For a long time the Russian Federation has been infected with several highly dangerous animal diseases, such as African and classical swine fever, FMD, lumpy skin disease, sheep and goat pox, and highly dangerous avian influenza. The specified above infections cause great damage to animal husbandry in the country which has a negative impact on its export potential. Analysis of the ASF epidemic situation demonstrates that the Russian Federation has been permanently infected and there is a trend for the geographic spread of the epidemic. Despite the fact that the number of ASF outbreaks newly detected in 2018 is almost half that of 2017, the situation remains tense. The forecast is still unfavorable. Lumpy skin disease has been reported in the Russian Federation for four years already. Herewith, from year to year the disease has been invading new territories. The HPAI epidemic situation is of great concern as in 2018 82 outbreaks were reported in poultry population which is 2.3 times more than in 2017. Besides, there is a trend for the epidemic extension. Thus, in 2018 avian influenza was reported in previously disease free Subjects of the Russian Federation. In 2018 the Russian Federation remained permanently infected with FMD, sheep and goat pox, and classical swine fever.

The paper presents the results of monitoring tests performed in the FGBI “ARRIAH” Branch in 2018 to detect AIV circulation in the Republic of Crimea. As AIVs are most frequently detected in aquatic and semiaquatic birds wild waterfowl present the greatest threat of the disease introduction and spread. That’s why the paper gives special attention to the Azov Sea and Sivash water area and describes natural biotopes of the Central and Eastern Sivash. During expeditions biological material samples were collected, bird species were identified and bird fauna was estimated in waterfowl aggregation sites. Laboratory PCR tests of the biological material collected during the expedition as well from killed birds and poultry revealed no AIV type A. As the number of wildfowl in the their usual aggregation sites decreased due to the fact that fresh water supply through the North-Crimean Canal ceased it can be assumed that the Crimean peninsula will manage to maintain HPAI freedom despite the fact that the disease is being reported close to the peninsula. Nevertheless, the threat of the virus introduction to the commercial and backyard farm stocks still exists as the peninsula is located in the bird migration routes and AI epidemical monitoring is a topical task.

Analysis of literature on avian influenza (AI) virus transmission through incubation eggs and qualitative assessment of risk of incubation egg import to the Russian Federation in the contest of veterinary and sanitary measures against avian influenza currently in place for imported products are presented. Probability of low-pathogenic AI virus transmission through poultry incubation eggs due to possible contamination of the egg and package surfaces with the said agents is indicated. Probability of AI virus transmission through commercial eggs derived from quails, turkeys, geese, chickens is shown to be high. Evidence of actual vertical transmission of highly pathogenic avian influenza virus is limited, however, it is recognized that the infection manifests by systemic lesions in the organs (bursa, thymus, spleen, heart, pancreas, kidneys, brain, trachea, lungs, adrenals and skeletal muscles). It is noted that the virus can persist on bird feathers and in bird meat for a long period. In addition, high humidity, neutral pH level and low temperature are shown to be favourable conditions for the virus survival in the ambient environment. Incubation egg movement restrictive measures are considered the most adequate for prevention of the disease spread between holdings. It is underlined that no country can guarantee the absence of the risk of avian influenza occurrence in avifauna. Anti-AI measures for incubation egg importation recommended by the World Organization for Animal Health are considered adequate for prevention of international disease spread regardless of the virus pathogenicity.

Epidemic patterns of highly pathogenic avian influenza А/Н5N8 spread in the Russian Federation are demonstrated, history of the disease outbreak eradication in domestic poultry is described, basic reasons of the dangerous virus introduction on the commercial farms are analyzed and issues of the outbreak containment are highlighted. Specific properties of H5N8 disease progression and clinical manifestation are demonstrated against H5N1 disease. Data of epidemic investigations of the virus introduction to the closed-type farms are integrated. Basic attention is given to the destruction of poultry died and stamped out during implementation of anti-epidemic measures, and potential alternative ways of biological waste destruction are demonstrated. Principal risks of introduction of emerging influenza virus subtypes into the Russian Federation are determined. Further spread of avian influenza over the Russian territory is expected due to the current epidemic situation, the virus persistence in the vectors, maintenance of its viability in the environment and seasonal migrations of the wild birds. Major threat of the agent introduction comes from the neighbouring East Asia and Far East countries (China, Japan, Korea). Herewith, introduction of potentially zoonotic viruses is also possible. Risk of the virus introduction from the European countries, Near East countries and Central Asia cannot be excluded. For now, drastic measures still remain the only tool for the disease control and the strategy of limited targeted AI vaccination in the backyards minimizes the virus introduction to the commercial farms located in the risk zones.

The paper is devoted to wide spread of avian influenza virus in the world and the disease prevention and control in Russia. It is necessary to monitor efficacy of inactivated vaccines against avian influenza caused by the currently circulating epizootic strains due to the virus evolution and variability. Reassortment of influenza A virus poses a serious threat to effectiveness of vaccination as an alternative to drastic measures. The message of the paper is to demonstrate how to better meet new challenges from the perspective of time.

Most of HPAI cases are associated with the periods of birds' migration to wintering and nesting areas. The last H5N1 cases in Russia were caused by virus introduction into backyards with hunting trophies (Primorsky Krai, 2008; Altay-sky Krai, 2014). The said cases prove the indisputable role of migrating wild birds in influenza virus circulation and spread maintenance. Today the only effective way to protect commercial poultry farms is a strict compliance with the biosecurity rules for closed poultry farms. Speaking about the threat ofavian influenza introduction the most vulnerable sectors are small farms and backyards where free ranged poultry is kept. The paper presents the analysis of H5 HPAI outbreak causes in the territory of the Altaysky Krai in 2014and eradication activities.

The following paper provides the analysis of epidemic situation on notifiable avian influenza for 2014and for thefirst quarter of 2015 based on the OIE data.Today the Al situation remains tense due to the spread of AIV subtypes H5N1, H5N2, H5N3, H5N6 and H5N8.The latter became widely spread both in domestic and wild birds starting from 2014. Taking into account spring the upcoming autumn bird migration, the risk of Al virus introduction and spread in the territory of the Russian Federation increases.

The paper demonstrates results of long-term monitoring research performed by the FGBI "ARRIAH" in the Russian part of Uvs-Nuur Lake water area in the Republic of Tyva. The monitoring was aimed at the detection of influenza A virus circulation in the population of wild migratory birds. Ecological and biological significance of the lake coastal area in the arrangement of epidemiological investigations was determined. Highly pathogenic avian influenza virus circulation was identified in populations of wild avifauna in Uvs-Nuur migration area.

The aim is to analyze the long-term results of the avian influenza virus surveillance monitoring of influenza virus in birds of one of the key Northern Eurasia points Lake. Uvs Nuur, the Republic of Tyva. Methods. The analysis of the available sources and our own research results is conducted. We used MEGA 5.2 software to construct a phylogenetic dendrogram. Tree topology is constructed by the method of maximum likelihood. Genetic distance matrix is calculated using the Kimura two-parameter metric method. Results. We conducted a biogeographical analysis of the Great Lakes basin, and an overview of the literature and the original results of highly pathogenic H5N1 influenza circulation and molecular epidemiology at Uvs Nuur Lake. Conclusion. Long-term observations at Lake Uvs Nuur revealed the important role of the biogeocoenose for the preservation and evolution of influenza A virus in wild bird populations. Planned ecological and virological monitoring is the basis for correct conclusions about the dynamics of epizootic process, infection control, as well as for the evaluation of the epidemic and pandemic potential of novel viral strains.