Veterinaarmeditsiini ja loomakasvatuse instituut
Selle valdkonna püsiv URIhttp://hdl.handle.net/10492/2469
Sirvi
Sirvi Veterinaarmeditsiini ja loomakasvatuse instituut Märksõna "African swine fever" järgi
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Kirje Epidemiology of African swine fever in Estonia and characterization of one virus strain(Eesti Maaülikool, 2021) Nurmoja, Imbi; Viltrop, Arvo; Blome, Sandra; Depner, Klaus Robert; Dixon, Linda (opponent)African swine fever (ASF) is an OIE-listed, dangerous viral disease of pigs, which has a devastating impact on animal health and the pig industry in many countries worldwide. During the period 2014–2020, ASF has been the main animal health issue in Estonia. This dissertation consists of three independent studies, which have been conducted with the aim to analyse the epidemiology of ASF and the course of the epidemic in the Estonian wild boar population, as well as in domestic pigs. In Study I, wild boar surveillance data (n = 7,015) collected from two distinct study areas from September 2014 to September 2016 were analysed. A statistically significant difference between the two areas in the temporal course of ASF seroprevalence was found. These findings indicate that ASF might have been introduced to the north-east of Estonia earlier then to the south of the country. The probability of detecting an ASF-positive animal was higher in young animals (< 1 year). Within wild boar found dead, there was a higher probability of finding an ASF-positive result compared to hunted animals. In Study II, the biological characteristics of the ASF virus strain (Est 14/WB) circulating in the wild boar population of north-east Estonia in 2014 were evaluated. Oronasal inoculation of ten young wild boar led to an acute and severe course of the disease in all infected animals. Nine animals died and one animal recovered completely from the disease. In conclusion, the ASFV strain was still found to be highly virulent. In Study III, the epidemiology of ASF in all 26 domestic pig outbreak herds that occurred in Estonia during the period 2015–2017 was retrospectively analysed. On most of the farms, the first clinical signs were mild and not ASF-specific despite the high virulence of the circulating virus. The highest mortality (29.7%) was seen on backyard farms (1–9 pigs) and the lowest (0.7%) on large commercial farms (> 1000 pigs). The spread of the virus within farms was slow and the contagiousness of the virus was relatively low. Farms of all sizes and types have been at risk. The results suggest that the increase in ASF cases in local wild boar populations is the main risk factor leading to the infection of farms; 88% of domestic outbreaks occurred in areas where ASF virus was detected in wild boar prior to the outbreak, within a radius of 15 km from the outbreak farm.Kirje Sensitivity of African swine fever surveillance system for wild boar in Estonia(Eesti Maaülikool, 2022) Breukers, Eveliina Anni Maria; Viltrop, ArvoAfrican swine fever is a viral disease of domestic pigs and wild boar, causing huge economic losses in pig industry. The main aim of the study was to investigate the sensitivity of African swine fever surveillance system implemented for wild boar in Estonia on county level, based on ASF surveillance data from Estonian Veterinary and Food Authority. More specifically, the study wanted to assess if the number of sampled wild boar is sufficient to detect ASF in counties, where ASF positive animals have not been detected and what is the confidence of disease freedom in counties where ASF positive cases have not been detected over longer time periods. The data was analysed from 15 Estonian counties from 2018 to 2021. In total 26 449 wild boar samples were analysed. The data was analysed in EpiTools by using “Simple riskbased surveillance - calculation of surveillance sensitivity” calculator to calculate the surveillance system sensitivity on single county level for every year of the study period and then “Confidence of population freedom for multiple time periods” calculator was used to calculate the confidence of freedom for single and multiple time periods in every county using the outputs from sensitivity analysis. The results indicated that 64.8% of the time periods, the surveillance sensitivity reached the sufficient level (>95%). Simple cumulative confidence of freedom was sufficient (>95%) for 75.9% of the time periods and reached >95% by the end of the whole observation period for all counties, whereas equilibrium cumulative confidence of freedom, which is dependent on probability of introduction (set at 10%), didn’t reach sufficient level in any time period being 90% at maximum.