Spatio-temporal analysis of African swine fever (ASF) in wild boar (Sus scrofa Meridionalis) in relation to outbreaks in domestic pig in the territory of Local Health Agency (ASL) of Sassari, Sardinia (2014-2015)

African swine fever (ASF) is a viral disease that has been reported in Sardinia since 1978 in both domestic pigs and the wild boar. Aim of this work is to define the risk-level of ASF spread through the analysis of samples of... [ view full abstract ]

African swine fever (ASF) is a viral disease that has been reported in Sardinia since 1978 in both domestic pigs and the wild boar. Aim of this work is to define the risk-level of ASF spread through the analysis of samples of wild boars shot during the 2014-2015 hunting season in the territory of the ASL of Sassari, Sardinia and the space-time comparison with outbreaks in domestic pigs. The samples were classified according to sex and age of the wild boar, as estimated by the absence of molars (0-6 months of age) or the presence of one (6-18 months), two (18-30 months) or three molars (> 30 months). Blood samples were collected from 950 wild boars: 505 females and 445 males. The spleen from 335 females and 280 males was collected for virus detection. ASF diagnosis has been carried out by the Istituto Zooprofilattico Sperimentale of Sardegna. Forty two females (22 aged > 30 months, 11 (18-30 months), 8 (6-18 months), 1 of 0-6 months) and 35 males (24 aged> 30 months, 9 (18-30 months), 2 of 6-18 months) were seropositive (Immunoblotting) and 5 female, 5 male adults were virologically positive (PCR-Real Time). All the data and the hunting sites were georeferenced and analyzed on a GIS system in relation to outbreaks of ASF in domestic pig (48 in 2013, 8 in 2014).The spatio-temporal analysis of the above results shows that seropositive young and sub-adults wild boars (0-18 months) and virologically positive wild boars were only hunted in areas where outbreaks of ASF in domestic pigs had previously occurred suggesting that virus introduction occurred first in domestic pigs. The analyses of these data and results can provide a valuable support for the redefinition of low and high risk areas for the spreading the ASF.