Six more cases of “deformed lamb disease” have been found in East Anglia, animal health officials confirmed.

A total of 11 cases of Schmallenberg virus (SBV) have been identified in early lambing flocks, according to the Animal Health and Veterinary Laboratories Agency.

Three of the new cases have been found in Suffolk, two in Essex and another one in Norfolk, which tends to suggest that the midge-borne virus spread from mainland Europe. And a case has been found in Kent for the first time.

The SBV disease, which was first identified in November last year in calves in northern Germany, hence the name, infects ruminants, including sheep, cattle and goats.

A North Norfolk veterinary surgeon took samples late last month when about 25 severely deformed lambs were found in an early lambing flock of about 200 ewes. These samples, which were sent to Bury St Edmunds for further checking, were matched at the AHVLA’s Weybridge laboratory.

Last week, it was revealed that the country’s first cases had been found in two sheep flocks, two in Norfolk, one in Suffolk and another in East Sussex.

It has infected dairy and beef cattle in Germany. In Holland and Belgium, ewes seem to be particularly susceptible and severely deformed lambs have been born but have not survived. In Holland, more than two-thirds of sheep tested for SBV were positive.

Spread by insects, mainly midges, it is possible that the mild and warm conditions early last autumn enabled newly-pregnant ewes to be bitten.

The human health risk is regarded as very low but farmers are advised to report symptoms to their vet although the disease is not notifiable. No live test is yet available.

SBV, which has been under investigation since August last year, can reduce yields and cause fever and diarrhoea in cattle. Symptoms have not been seen in cattle in Britain, said a Defra official.

The virus is a completely different type from Blue Tongue. The first case of Blue Tongue (BTV8) in England was confirmed on a Suffolk farm near Ipswich in August 2007 and the following year, a major vaccination campaign was launch to protect cattle and sheep from infection. It was thought to have been found on more than 50,000 farms in Europe.