Changes

===Vector Competence===

===Vector Competence===

3.9 The C. obsoletus group has long been suspected of being a vector, mainly on

 

the basis of BTV isolations from this species made in Cyprus, and African horse

Certain information can help inferences be made regarding BTV vectors in Britain. Both ''C. obsoletus'' and ''C. pulicaris'' have been implicated in transmission before. Previously, BTV has been isolated from ''C. obsoletus'' in Cyprus, and African horse sickness virus (another Orbivirus) in Spain. ''C. obsoletus'' and ''C. pulicaris'' were also the most abundant ''Culicoides'' species detrected in the 1999 BTV epizootic in Greece and Bulgaria, and so are strongly suspected of acting as vectors in this case. They may also have mediated outbreaks in Serbia, FYR Macedonia, Croatia and Bosnia in 2001-2002, where ''C. imicola'' has not been recorded.

sickness virus (AHSV) isolations made from mixed pools of C. obsoletus and C.

 

pulicaris in Spain. In this context it should be borne in mind that BTV and AHSV tend

to utilise the same Culicoides species as vectors.

as BTV vectors in northern Greece and southern Bulgaria during the 1999 BTV

epizootic, as they were by far the most abundant and most prevalent detected. It is

similarly suspected that these species may also have mediated the BT outbreaks in

Serbia, western and southern Bulgaria, FYR Macedonia, Croatia and Bosnia during the

period 2001-2002. C. imicola has not been recorded in these regions.

3.11 Vector competence studies on a British population of C. obsoletus have

3.11 Vector competence studies on a British population of C. obsoletus have

recorded oral susceptibility rates of less than 2% in comparison with a known major

recorded oral susceptibility rates of less than 2% in comparison with a known major

in Australia, has an experimental competency of only 0.3 percent when feeding on

in Australia, has an experimental competency of only 0.3 percent when feeding on

sheep although it is quite an effective vector in the field.

sheep although it is quite an effective vector in the field.

===Epidemiology===

===Epidemiology===