The Schmallenberg virus has spread to 40 holdings in the UK, according to figures released by the Animal Health and Veterinary Laboratories Agency.
The pattern of the disease spread remains consistent with the agency's belief that the disease has been carried by infected midges, blown from affected areas in mainland Europe last summer.
All of the virus-infected holdings are in the south and east of England within counties which have been identified by the agency as potentially at risk.
Counties affected are Norfolk, Suffolk, Essex, Kent, East Sussex, West Sussex and Hertfordshire.
With the exception of one virus-positive cattle sample, from a farm in West Sussex, all of the GB cases have been diagnosed in sheep to date.
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