Spatial-temporal Trends and Factors Associated with the Bluetongue Virus Seropositivity in Large Game Hunting Areas from Southern Spain.

An epidemiological study was carried out to determine the spatial-temporal trends and risk factors potentially involved in the seropositivity to bluetongue virus (BTV) in hunting areas with presence of red deer (Cervus elaphus). A total of 60 of 98 (61.2%; CI95% : 51.6-70.9) hunting areas sampled presented at least one seropositive red deer. Antibodies against BTV were detected in juvenile animals during the hunting seasons 2007/2008 to 2013/2014 in 15 of 98 (15.3%) hunting areas, which indicates an uninterrupted circulation of BTV in this period. A multivariate logistic regression model showed that the red deer density at hunting area level (>22 individuals/km(2) ), the annual abundance of Culicoides imicola (>1.4 mosquitoes/sampling) and the goat density at municipality level (>24.1 individuals/km(2) ) were factors significantly associated with BTV seropositivity in hunting areas. Control measures against BTV in the studied area include vaccination programmes in wild and domestic ruminants, movement control in areas with high densities and abundance of red deer and C. imicola, respectively. Considering the potential risk of BTV re-emergence, red deer should be included in the BT surveillance programmes in regions where these species share habitats with livestock.