Changes

Bluetongue Virus (view source)

Revision as of 13:12, 20 August 2010

902 bytes removed , 13:12, 20 August 2010

Line 22: Line 22:

===Vectors===

−

The arthropd vector for bluetongue virus is the ''Culicoides'' biting midge. These insects breed in damp soil enriched with ~~dung~~ and ~~take blood meals from vertebrate hosts~~.

+

The arthropd vector for bluetongue virus is the ''Culicoides'' biting midge. These insects take blood meals from vertebrate host and breed in damp, dung-enriched soil enriched, and so are abdunant in the vicinity of domestic livestock. 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.

−

~~Since appropriate breeding sites are very common around livestock~~

−

~~holdings Culicoides are particularly abundant at such sites and therefore feed~~

−

~~predominantly upon domestic livestock (cattle, horses, sheep). They rapidly become~~

−

~~much less abundant as distances from livestock holdings increase. Culicoides tend to~~

−

~~be most active from about 1 hour before sunset until 1 hour after sunrise. They are~~

−

~~most active in the evening until about midnight, then ease off with another peak of~~

−

~~activity around sunrise. However, on dull days or in shady areas vectors may be active~~

−

~~during the day. On windy days, they tend to be less active. Measures to protect~~

−

~~susceptible animals from infection should particularly target these active periods. Most~~

−

~~Culicoides species, including the British species, are averse to entering confined~~

−

~~spaces such as buildings or vehicles, although small numbers might be brought inside~~

−

~~while biting a host and/or while host seeking.~~

3.2 Culicoides species have a normal insect complete metamorphosis life cycle –

egg, four larval instars, pupa and adult. In temperate and cool regions they

Line 46: Line 34:

Britain. The life span of adults is usually about 10 days, but in cooler conditions their

metabolism slows and they may survive for periods of more than a month.

−

~~Technical Review - Bluetongue: The Virus, Hosts and Vectors~~

+

−

~~___________________________________________________________________________~~

−

4.

−

~~Version 1.5; 21 November 2002~~

Most species require a blood meal before laying eggs, although C. impunctatus (the

Scottish highland biting midge), a member of the C. pulicaris group, does not require a

Line 89: Line 74:

efforts have not been made to collect rather than the species is absent there. Generally,

the insects congregate where there are breeding sites and hosts upon which to feed.

−

~~Technical Review - Bluetongue: The Virus, Hosts and Vectors~~

+

−

~~___________________________________________________________________________~~

−

5.

−

~~Version 1.5; 21 November 2002~~

Thus, the highest concentrations of C. obsoletus and/or C. pulicaris group midges are

found where cattle, horses, pigs and, to a lesser extent, sheep populations are highest.

Lizzies

6,502

edits