Bluetongue virus in the Campania region (southern Italy): high seroprevalence in both SBV exposed and non-exposed ruminants.

Bluetongue is a non-contagious arthropod-borne viral infection that is notifiable in several countries. The disease produces significant economic losses and is a main source of concern for ruminant commerce. Cattle are considered the reservoir of the bluetongue virus (BTV), which is responsible for huge economic losses on ruminant farms. In this study, we evaluated the seroprevalence of BTV in the Campania region, southern Italy, among the cattle and buffalo populations. The infection was widely spread, as attested by the high individual (43.6%) and herd prevalence (85.4%). We also evaluated the correlation between BTV seropositivity and various risk factors. The seropositivity rate did not differ between the two species considered or the type of housing. Surprisingly, seropositivity to SBV did not predispose animals to be positive for BTV, even though these infections share the same vector (Culicoides). A total co-infection rate of 21.8% was found. Age, on the other hand, was found to be a risk factor, as higher prevalences were found in adult animals. Among the climatic factors analyzed, a preponderant role is given by the average temperature, which is capable of influencing the probability of being positive for this infection. Our data, associated with those present in the literature, suggest that the spread of BTV is now transversal in the Mediterranean basin, that the rate of co-infection with SBV is not high, and that climate change has facilitated and continues to improve the spread of this virus.