Bluetongue disease: Encyclopedia - Bluetongue disease

Bluetongue disease

Bluetongue disease (also called catarrhal fever) is a non-contagious, arthropod-borne viral disease of ruminants, mainly sheep and less frequently of cattle, goats, buffaloes, deer, dromedaries and antelopes. There are no reports of human transmission. The pathogenic virus is a member of the Reoviridae. It is transmitted by a midge, Culicoides imicola and other culicoid species.

Bluetongue has been observed in Australia, the USA, Africa, the Middle East, Asia and Europe. Its occurrence is seasonal in the affected Mediterranean countries, subsiding when temperatures drop. It has been spreading northward since 1999.

Major signs are high fever, excessive salivation, swelling of the face and tongue and cyanosis of the tongue. Swelling of the lips and tongue gives the tongue its typical blue appearance, though this sign is confined to a minority of the animals. Recovery is very slow.

The incubation period is 5–20 days, and all signs usually develop within one month. The mortality rate is normally low, but is high in susceptible breeds of sheep. In cattle and wild ruminants infection is usually asymptomatic despite high virus levels in blood.

There is no efficient treatment. Prevention is effected via quarantine, inoculation with live modified virus vaccine and control of the midge vector, including inspection of aircraft.[1]

Although the tongues of human patients with some types of heart disease may be blue, this sign is not related to bluetongue disease.

Adapted from the Wikipedia article "Bluetongue disease", under the G.N U Free Docmentation License. Please also see http://en.wikipedia.org/wiki