The outbreak has struck more than 9000 animals in Germany, the Netherlands, France, Luxembourg and Belgium, and a temporary control area has been delared in Britain, where four cases have been confirmed.
A vaccine may be available for sheep and cattle by early next year.
Britain's fourth case occurred in a Holstein cow on a farm near Ipswich, Suffolk, about 80km from the other three cases on a rare breeds farm in Baylham.
The control zone covers Cambridgeshire, Northamptonshire, Lincolnshire, Leicestershire, Nottinghamshire, Bedfordshire, also Essex, Norfolk and Suffolk where additional controls apply.
Bluetongue is a similar midge-borne disease to African Horse Sickness, both of which have been spreading north for the last 20 years, possibly because of global warming.
The same species of midge can spread both diseases. Infected midges can potentially be blown for more than 100km by the wind and transported long distances in farm vehicles, making containment difficult.
Tests are being carried out in Suffolk to ascertain the disease's spread, and whether it has infected the native midge population.
An outbreak has not yet been declared, and Defra said today that "there is not sufficient evidence to confirm an active outbreak of Bluetongue as it cannot yet be demonstrated that the disease is circulating. Epidemiological investigations are on-going to establish whether bluetongue disease is circulating in the UK."
Action will be in line with the UK Bluetongue Control Strategy, published in August, but will also take account of the current FMD restrictions. Animal keepers must practice high standard of biosecurity, remain vigilant for disease and report any suspicions immediately. Livestock owners should examine their livestock twice a day.
Bluetongue, or catarrhal fever, can only spread by insect, and affects mainly sheep. It canalso infect cattle, goats, buffalo, deer, dromedaries and antelope.
Symptoms of Bluetongue include respiratory problems, swelling of the mouth, head and neck, fever, drooling, and lameness. An affected animal will have ulcers around the eyes, nose and mouth. Affected animals can recover. The disease is named for the characteristic swollen blue tongue that appears in the animal around death.
Bluetongue virus affects ruminants (sheep, goats, cattle) and can cause severe epidemics in sheep. The infection seldom causes disease in other susceptible ruminants, but infected cattle are a carrier of infection for other species.