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→Vectors
Classically, the major vector for BTV is ''Culicoides imicola''. This midge is found throughout Africa, the
Classically, the major vector for BTV is ''Culicoides imicola''. This midge is found throughout Africa, the
Middle East, southern Asia, Portugal, Greece, Corsica, Sardinia, Sicily and areas of Italy<sup>1</sup>, and its distribution appears to be extending northwards. However, ''C. imicola'' has not yet been demonstrated in the United Kingdom. The ''Culicoides'' species found in the British Isles are ''C. pulicais'' and ''C. obsoletus'', which are also common across central and northern Europe. Knowledge of the distribution of these species in the UK is incomplete, but in general the insects gather where breeding sites and hosts occur in tandem.
Middle East, southern Asia, Portugal, Greece, Corsica, Sardinia, Sicily and areas of Italy<sup>1</sup>, and its distribution appears to be extending northwards. However, ''C. imicola'' has not yet been demonstrated in the United Kingdom. The ''Culicoides'' species found in the British Isles are ''C. pulicais'' and ''C. obsoletus'', which are also common across central and northern Europe. Knowledge of the distribution of these species in the UK is incomplete but the insects tend to gather where breeding sites and hosts occur in tandem, with the highest midge concentrations in areas containing cattle, horses and pigs. Removal of livestock decreases populations of ''Culicoides'' by a factor of 10 to 20<sup>1</sup>, but some persist by feeding on wild animals and man. Hill sites have fewer midges as climatic conditions are less favourable, and sheep have a less positive influence on distribution.
In Britain, studies are ongoing to determine midge distribution, seasonal incidence and the competency of the various ''Culicoides'' species to act as BTV vectors.
species.
===Vector Competency===
===Vector Competency===