African horse sickness and the overwintering of Culicoides spp. in the Iberian peninsula.

Abstract

The presence at different latitudes and the seasonal distribution of two known or potential vectors of African horse sickness (AHS) virus--Culicoides imicola and C. obsoletus--were investigated in the Iberian peninsula using light trap collections. Culicoides imicola was present as far north as 41 degrees N but not at 43 degrees N (Asturias, Spain), whereas C. obsoletus was found at all latitudes. In the northern part of the distribution of C. imicola, adults of this species were present for only a few months of the year, but adults were continually present further south. Culicoides obsoletus could be found in all months of the year in the peninsula (as in southern Britain), despite cold winter conditions. These results were compared to data from the AHS outbreak in 1987-1990 in the Iberian peninsula, to indicate the potential for the disease to persist from year to year and expand more fully in the palaearctic regions of Europe.