Professor Matthew Baylis, Institute of Infection and Global Health, said:
“Eighty-three cattle and sheep farms in 14 counties of England are now known to have been infected with Schmallenberg virus. This is likely to be the tip of the iceberg, as detection currently relies on finding evidence of the actual virus in animals, which is difficult as viral infection is usually transitory.
“A better approach is to test for the antibodies that animals will have raised against the virus, and which then persist in the blood for months. However, no such serological test exists for Schmallenberg virus at present because the virus was only discovered, in Germany, a few months ago. When such a test is successfully developed, it is likely that much larger numbers of farms in Great Britain will be found to have been infected by the virus.
“Schmallenberg virus is transmitted by blood-sucking insects, and biting midges are the main suspects. In August of 2007 biting midges carrying a different virus, called bluetongue virus, were blown over to England from continental Europe, and in the outbreak that followed, about 150 cattle and sheep farms were infected, mostly in the south-east of England.
“A question regarding Schmallenberg virus is how it could already have spread over a large area of England if, as suggested by Defra, the most suitable times for infected midges to have been blown over to us from the continent was late October or early November. If the time of introduction was that late in the year, then Schmallenberg must somehow be capable of faster spread than bluetongue and the prospects for cattle and sheep farmers across the UK in 2012 would not be encouraging.
“An alternative, and perhaps more likely explanation, is that Schmallenberg has been with us for some time, but was not noticed; it may even have been present in the UK at or before the time that the virus was first discovered last August in Germany.”
Read the latest BBC story on Schmallenberg virus.