Prisustvo virusa avijarne influence podtipa H5N8 kod divljih ptica u Srbiji 2021. godine

Abstract

Avian influenza (AI) is highly contagious infectious disease of birds that cause high health and economic loses to poultry industry, and in the same time, as zoonotic disease, represents the constant threat to human health. Avian influenza virus (AIV) is maintaining in the nature in the population of wild waterfowl that are natural hosts of this virus. During the second half of 2020, and especially at the beginning of 2021, a large epizootic of AI occurred. The area of Europe is affected by a large number of outbreaks of AI, especially in the second half of 2020 and in the beginning of 2021, with the largest number of cases caused by highly pathogenic AI virus strains (HPAI) of subtype H5N8, as well as some other strains of H5 virus subtype. In Serbia, according to the Program of Measures of Animal Health, passive surveillance of the occurrence of AI is carried out, which includes examination of the presence of AIV in cases of found dead wild birds (suspicion of infectious disease in susceptible bird species and natural hosts), as well as examination of causes of death (suspected infectious disease) with an increased number of deaths in flocks of domestic poultry. The detection of AIV presence was done in the tissue samples of found dead wild birds belonging to different species. Testing’s were done by real-time RT-PCR method with primers specific for the matrix gene of all influenza viruses, and after the confirmation of virus presence, additional testing’s were done with primers specific for different virus subtypes. The first positive case of avian influenza in Serbia in the 2020/2021 season was determined on March 2, 2021 in swans in the settlement of Kula, Kula municipality on the Veliki Bački Canal, where the presence of HPAI virus of the H5N8 subtype was determined in the dead individuals. During the implementation of passive surveillance in 2021 in the period until April 24, a total of 10 wild bird samples (8 swans, 1 starling and 1 marsh eagle) from the area of 5 locations in 2 districts in Vojvodina Province were examined. The presence of AIV subtype H5N8 was determined in 6 (60%) examined individuals from 2 locations (settlements Kula and Sivac). Of the wild birds examined, a positive finding for AIV was found only in swans (in 6 of 8 examined individuals). There were no major domestic poultry agglomerations (intensive poultry farming) in the infected and area under surveillance, and so far there have been no significant economic damages. Considering to the obtained results, as well as the still unfavourable epizootic situation of AI in the whole of Europe, it is necessary to establish a program based surveillance of influenza virus in the territory of the Republic of Serbia in the future.