SPATIO-TEMPORAL ANALYSIS OF THE LOCAL AFRICAN SWINE FEVER SPREAD IN THE RUSSIAN FEDERATION IN 2007–2015

African swine fever (ASF) is a viral disease of domestic and wild pigs, which since its first recording in 2007 has been spreading over the territory of the Russian Federation (RF) affecting both pigs at private and large commercial farms, and wild boars. The disease leads to nearly 100% mortality of infected animals and causes huge economic losses to the national pig industry. The study deals with characteristic features of the ASF spread in the RF and the spatio-temporal patterns of local epizootic development. The Kulldorff space-time scan statistics was used as a cluster analysis method. The ASF outbreak spatiotemporal clusters were identified in: 1) domestic pig populations, 2) wild boar populations and 3) the cumulative populations of both. The main quantitative parameters of clusters including the radius, duration and the observed number of outbreaks were obtained. The correlation between the number of outbreaks within each cluster and the geographical factors which supposedly facilitated the disease spread were analyzed. A total of 17, 9 and 17 statistically significant ASF outbreak clusters were identified in domestic pig, wild boar and cumulative populations respectively. It was concluded that the wild boar population should not be viewed as a primary source of the disease spread in the RF. A strong positive correlation between the observed number of outbreaks in domestic pigs and the total motorway length, total pig population and the number of rural settlements within the clusters was revealed. The number of outbreaks in wild boars and the forest-covered area within the clusters were also found to correlate significantly. The results make it possible to develop a geospatial model for predicting local ASF spread in case of the ASF introduction into disease-free regions.

African swine fever, cluster analysis, local epizooties, geospatial factors

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