Role of wild boars and domestic pigs in the spread of African swine fever in the Russian Federation (2007-2013)

text: African swine fever (ASF) is a highly contagious and fatal disease of domestic pigs, feral pigs and wild boar. In the last years (2007-2013) 683 outbreaks of ASF were reported in the Russian Federation (RF) (292 in wild boars and 391 in domestic pigs) causing significant economic losses in the swine industry. The recent introduction of ASF in wild boars in EU increases the risk for other EU-member countries. The role of wild boar in the epidemiology of the disease in RF is not yet completely understood. Therefore a better understanding about related risk factors associated with the presence of ASF in wild boar in RF is still required in order to develop and focus programs to control or prevent the spread of ASF. The objective of this study was to identify the environmental risk factors associated with outbreaks of ASF in wild boars in RF (2007-2013). To do it, a case-control study was conducted using a generalized linear model (GLM). Cases were defined as those areas where significative spatiotemporal clusters of ASF outbreaks in wild boars had been identified using a scan statistics permutation analysis (nine case areas) (Iglesias et al., 2014*). Eighteen randomly selected areas were defined as ”control areas”. Ten environmental variables (climatic and biological) selected because their importance in the biology of ASF virus, were explored comparing their mean values between cases and control areas. Those variables associated (Kruskall-Wallis test) with sanitary status of the areas and without significant correlation (Pearson test) among them were included in a GLM analysis The model that best fitted the data (AIC=30.99) included “wild boar presence” as predictor variable (P < 0.05) (b=9.2). ”Maximum isolation” could be included but showed a low effect on the probability of occurrence of the event (b=0.004) and showed a high correlation with wild boar presence. A subsequent analysis indicated that the number of ASF domestic pigs cases showed a high association with cases/control areas (KWH=11.16; p=0.0008). Results could be interpreted as environmental factors might not be as relevant as ASF domestic pig cases in the ASF transmission in wild boar. For a deeper analysis of this finding, a spatiotemporal analysis of interactions between domestic and wild ASF cases was developed (results showed in Iglesias et al., 2014**). * Iglesias et al., 2014. Título. Identification of the Reproductive ratio for the local spread of African swine fever in wild boars in the Russian Federation. EPIZONE 2014 comunication. ** Iglesias et al., 2014. Título. Role of wild boars and domestic pigs in the spread of African swine fever in the Russian Federation (2007-2013)EPIZONE. Identification of the Reproductive ratio for the local spread of African swine fever in wild boars in the Russian Federation Irene Iglesias , MaJesús Muñoz, Marisa Arias, Fernando Montes,Andrés Pérez,Andrey Gogin,Denis Kolbasov, Ana de la Torre 1 Epidemiology & Environmental Health Department of Animal Health Research Center