Update on the risk of introduction of African swine fever by wild boar into disease-free European Union countries

Abstract

Despite efforts to prevent the appearance and spread of African swine fever (ASF) in the European Union, several Member States are now affected (Lithuania, Poland, Latvia and Estonia). Disease appearance in 2014 was associated with mul_x0002_tiple entrances linked to wild boar movement from endemic areas (EFSA Journal, 8, 2015, 1556), but the risk of new introductions remains high (Gallardo et al., Porcine Health Management, 1, 2015b and 21) as ASF continues to be active in endemic countries (Russian Federation, Belarus and Ukraine). Since 2014, the number of ASF notifications has increased substantially, particularly in wild boar (WB), in parallel with slow but constant geographical advance of the disease. This situation suggests a real risk of further disease spread into other Member States, posing a great threat to pig production in the EU. Following the principles of the risk-based veterinary surveillance, this article applies a methodology developed by De la Torre et al. (Transboundary and Emerging Diseases, 62, 2015 and 272) to assess the relative risk of new introductions of ASF by natural movements of WB according to the current epidemiological situation. This update incorporates the most recent available data and an improved version of the most important risk estimator: an optimized cartographic tool of WB distribution to analyse wild boar suitable habitat. The highest relative risk values were estimated for Slovakia (5) and Romania (5), followed by Finland (4), Czech Republic (3) and Germany (3). Relative risk for Romania and Finland is associated mainly with disease entrance from endemic areas such as the Russian Federation and Ukraine, where the dis_x0002_ease is currently spreading; relative risk for Germany and Czech Republic is asso_x0002_ciated mainly with the potential progress of the disease through the EU, and relative risk for Slovakia is associated with both pathways. WB habitat is the most important risk estimator, whereas WB density is the least significant, suggesting that WB presence is more relevant than density. These results can provide action_x0002_able advice for dealing with risk. They can be directly used to inform risk-based national strategies and identify countries that may need to pay greater attention to surveillance or conduct additional evaluations at the subnational level.