The dynamics and features of the manifestation of highly pathogenic avian influenza A/H5N1 were studied on the territory of the Republic of Tuva, where it was first recorded in 2006 in wild migratory waterfowl of the duck family, mainly great crested grebe ducks. In the epizootic process of highly pathogenic avian flu on the territory of the Republic, causal-temporal relationships with the seasonal migration of wild waterfowl from the countries of South-East Asia have been noted. Epizootics of highly pathogenic avian flu were observed in 2006, 2009, 2010, 2014, 2015, 2016. In 2016, as a result of mutation of the H5N1 virus strain, an outbreak of highly pathogenic avian flu of the H5N8 strain was registered. Outbreaks of highly pathogenic avian flu H5 and H7 subtypes simultaneously with low pathogenic subtypes of avian flu H3 were noted in 2014, H9 – in 2013 and 2014. In the study of blood serum of birds in the years officially free from avian flu, antibodies to hemagglutinins of the virus of different subtypes were detected in 11.2-50.0% of cases. Despite the absence of bird mortality, this indicates a constant circulation of avian influenza agent in the body of waterfowl. On the territory of the Republic, avian flu has not spread among poultry due to natural-geographical, socio-economic conditions. The development of distant pasture farming does not provide for the maintenance and breeding of poultry in the unfavorable area of the lake UvsNuur; the local population does not have a tradition of hunting for wild fowl, which prevents contact between wild and domestic birds; there are no lakes or pond reservoirs near the only poultry farm in the Republic with a small stock, which prevents wild waterfowl from entering and passing through flying passages.
Epidemiology of H5N8 Highly Pathogenic Avian Influenza (HPAI) in the Republic of Korea
