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→Transmission and Epidemiology
The arthropd vector for bluetongue virus is the ''Culicoides'' biting midge. These insects take blood meals from vertebrate hosts and breed in damp, dung-enriched soil enriched, and so are abdunant in the vicinity of domestic livestock. Once eggs are laid in soil, ''Culicoides'' progresses through four larval stages and pupates before becoming an adult midge. The lifecycle is greatly influenced by temperature: in temperate regions such as Britain, the adult midge population declines in October and is absent by December. The fourth larval stage overwinters, and adults re-appear the following April. In warm conditions, adults survive around 10 days, but this can be extended to up to a month when the weather is cooler. The activity of ''Culicoides'' varies with the time of day: the midges are most active at night, from an hour before sunset to an hour after sunrise. Activity is decreased by windy conditions, and increased during the day when the weather is dull. ''Culicoides'' generally avoid entering buildings and other closed spaces.
The arthropd vector for bluetongue virus is the ''Culicoides'' biting midge. These insects take blood meals from vertebrate hosts and breed in damp, dung-enriched soil enriched, and so are abdunant in the vicinity of domestic livestock. Once eggs are laid in soil, ''Culicoides'' progresses through four larval stages and pupates before becoming an adult midge. The lifecycle is greatly influenced by temperature: in temperate regions such as Britain, the adult midge population declines in October and is absent by December. The fourth larval stage overwinters, and adults re-appear the following April. In warm conditions, adults survive around 10 days, but this can be extended to up to a month when the weather is cooler. The activity of ''Culicoides'' varies with the time of day: the midges are most active at night, from an hour before sunset to an hour after sunrise. Activity is decreased by windy conditions, and increased during the day when the weather is dull. ''Culicoides'' generally avoid entering buildings and other closed spaces.
3.4 Culicoides imicola is the major vector of BTV in the Old World. It is one of the
3.4 Culicoides imicola is the major vector of BTV in the Old World. It is one of the
most widely distributed of Culicoides species. It occurs throughout most of Africa, the
most widely distributed of Culicoides species. It occurs throughout most of Africa, the
common throughout central and northern Europe. Both of these species are widespread
common throughout central and northern Europe. Both of these species are widespread
throughout most of the British Isles.
throughout most of the British Isles.
3.7 The distributions of C. obsoletus and C. pulicaris group midges in UK are not
3.7 The distributions of C. obsoletus and C. pulicaris group midges in UK are not
well understood. Observations of both have been made in many parts of the British
well understood. Observations of both have been made in many parts of the British