March 28, 2008

Evidence is mounting that deadly bluetongue - an insect-borne disease of sheep and cattle closely related to African horse sickness that is spread by the same midges - could hit England with a vengeance this northern spring.

Bluetongue is present in many countries worldwide, with various strains having been present in the Mediterranean area for some time. In 2006, a new strain, bluetongue serotype 8, began to circulate in northern European countries such as Germany, Belgium, Luxembourg, Holland, and France. In 2007, it appeared for the first time in Britain, in East Anglia.

British Agriculture Minister Michelle Gildernew told parliament this month, in outlining the discovery of bluetongue in an imported dairy heifer in February, that last autumn's incursion of bluetongue was believed to be the result of wind-borne midges arriving from the Continent via a prevailing easterly weather pattern.

"That incursion has established a beachhead of infection in South East England that could spread north and west this summer by midge activity," she said.

"However ... the more immediate threat to the North and the more likely way the disease could arrive here is through imports of infected animals from bluetongue infected areas in Britain and the Continent. That is why I have been encouraging farmers here not to import animals from such regions."

"It is imperative that we seek to hold bluetongue out as long as is possible."

Meanwhile, there is evidence that the virus has survived in animals from the outbreak last autumn, raising the spectre that it will be spread again this spring once the midges become active in warmer weather.

While the disease is often fatal in sheep, cattle can withstand the infection better and clinical signs are not always evident.

Experience in Continental Europe shows that a handful of cases one year can lead to thousands the next - as happened in Belgium, the Netherlands, Germany, Luxembourg, and in northern France.

Protection zones are in place around where the 60 cases were recorded last autumn and 101 properties are under special additional restrictions.

The British government is gearing up for a fight, with more than 22 million doses of vaccine on order in case it is needed.

Meanwhile, Italy has also reported an outbreak, in four cattlebeast. The affected farm is in the Verona area, in the northern part of the country.

Movement controls, screening and zoning have been used to control the outbreak.

Related African horse sickness has spread north from Africa and has caused horse deaths in several European countries. It has a high fatality rate and is considered a major disease threat to northern European horses, which have never been exposed to it.