Spatio-temporal kriging analysis to identify the role of wild boar in the spread of African swine fever in the Russian Federation

The current situation of African Swine Fever (ASF) epidemic in continental Europe represents a serious economic risk for the European pig industry. It is well known that both domestic pigs and wild boar are involved in the ASF spread, but the exact mechanism of the domestic–wildlife interface remains under research. A spatio-temporal kriging analysis was carried out to estimate the most possible source of infection (domestic pigs or wild boar) for 1,323 notifications of ASF reported in the Russian Federation (RF) from 2013 to 2017. Results for the whole period of study showed that domestic pigs and wild boar were the potential source of infection for 55% and 45% of notifications, respectively. The analysis stratified by year showed fluctuation in this tendency through time. At the early stages of the ASF epidemic in the Southern regions of the RF in 2007–2008 wild boar appears to be the main source of infection, while the following stage of the epidemic in 2009–2012 may be more related to a domestic source of infection. At the latter stage of the epidemic (2013–2017) both, domestic and wild boar, play a similar role as a source of the disease in the newly infected areas but differences by geographical locations can be observed matching with the epidemiology of the disease. This paper provides useful information for better understanding of the ASF mechanism and domestic–wildlife interactions in the RF and describes a new spatio-temporal approach that can be easily applied to other similar animal diseases with a domestic–wildlife interface.