In the

case of human-to-human Culicoides-transmitted arboviruses in sub-Saharan Africa, epidemics of febrile illness in humans on the scale of OROV outbreaks in Brazil would be visible even against a background of high malaria or dengue prevalence. The circulation of undetected low level endemic transmission of OROV or OROV-like arboviruses in Africa, however, cannot be easily discounted. Additionally, this region supports substantial banana and plantain CCI-779 datasheet production and possesses Culicoides species occupying a similar ecological niche to C. paraensis in both larval habitat and human biting habits, most obviously C. fulvithorax ( Agbolade et al., 2006 and Glick, 1990). Sub-Saharan Africa has also provided many of the isolates of zoonotic arboviruses from Culicoides recorded to date ( Table 2) and these could be imported directly into Europe via individuals or animals with transmissible infections. Following introduction, the onward transmission and establishment buy PD98059 of a Culicoides-borne arbovirus in Europe would require fully infected Culicoides to locate and bite susceptible hosts on release from shipments, or would require viraemic hosts to come into contact with sufficiently abundant local biting populations of susceptible Culicoides adults to permit transmission. The survival of imported exotic Culicoides and the proximity

of susceptible hosts capable of developing a transmissible viraemia to points of incursion is likely to be a major determinant of the probability of 4��8C successful establishment of arboviruses in a new area. Indirect evidence of indigenous Culicoides developing in close proximity to and feeding on exotic animals has been provided from studies of zoos, both globally and

in Europe ( Labuschagne et al., 2007, Nelder et al., 2010 and Vilar et al., 2011). However, the vector competence of European Culicoides species for OROV and zoonotic arboviruses is currently unknown, however, and would significantly influence their onwards transmission potential. Assuming that the major human and livestock-associated species have at least a degree of competence for the introduced arbovirus, several aspects of the biology of these species would then be expected to influence the likelihood of onwards transmission and spread, such as habitat preference and population structure. In terms of high abundance and rate of human contact, the most likely current candidate for sustained human-to-human transmission of arboviruses in Europe is C. impunctatus. This is particularly true in areas where larval habitat of C. impunctatus overlaps with permanent human populations in Scotland ( Fig. 2). Several uncertainties underlie this assumption, however, and remain to be addressed.