Changes

It is appears that in different regions of the world, specific serotypes of bluetongue virus have co-evolved with vector species of insect vector⁷. For example, different serotypes of BTV are prevalent in the USA to those in those the Caribbean and Central America although there is no real geographic barrier separating these areas, and animals move between the regions. This is thought to be due to the variation in the species of vector insects: ''Culicoides sonorensis'' is the primary vector in the USA and is most competent for serotypes 10, 11, 13 and 17, but in the Caribbean and Central America ''C. insignis'' carries serotypes 1, 2, 3, 4, 6, 8, 11, 12, 13, 14 and 17⁴.  

It is appears that in different regions of the world, specific serotypes of bluetongue virus have co-evolved with vector species of insect vector⁷. For example, different serotypes of BTV are prevalent in the USA to those in those the Caribbean and Central America although there is no real geographic barrier separating these areas, and animals move between the regions. This is thought to be due to the variation in the species of vector insects: ''Culicoides sonorensis'' is the primary vector in the USA and is most competent for serotypes 10, 11, 13 and 17, but in the Caribbean and Central America ''C. insignis'' carries serotypes 1, 2, 3, 4, 6, 8, 11, 12, 13, 14 and 17⁴.  

A variety of other hosts have been implicated in the lifecycle of BTV infection. Serological evidence indicates that large African carnivores are infected with BTV, whereas smaller predators that co-habit with them are not, suggesting that large carnivores are infected through feeding on BTV-infected ruminants [2]. Inadvertent contamination of a canine vaccine with BTV confirmed that dogs are susceptible to BTV infection, indeed pregnant bitches that received this contaminated vaccine typically aborted and died [1]. There is no evidence, however, that dogs or other carnivores are important to the natural cycle of BTV infection.

Bluetongue virus infection was first confirmed in the UK in September 2007 when a veterinarian spotted suspicious clinical signs on a cattle holding near Ipswich⁸. There are several possibilities for how the virus spread to the British Isles: a) through transport of infected animals; b) by local vectors acquring virus from infected animals (unlikely given the island geography of the UK), or c) via movement of vectors carrying BTV. It is believed that BTV-laden vectors were dispersed to the UK on the wind, since meteorological conditions on 4th August 2007 were capable of carrying midges from northern Europe to East Anglia. This would be expected to produce disease at a point that would coincide with the first case, given the time necessary for clinical detection to occur.

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