Another “deformed lamb disease” case has been found in Norfolk.

In total, 11 cases of Schmallenberg virus (SBV), three in Norfolk and four in Suffolk, have been offically confirmed. Vets at the Westover’s practice have confirmed a new case.

Former senior partner, Graham Duncanson briefed about 30 flock owners at Westover’s large animal centre at Manor Farm, Hainford, near Aylsham, about sheep topics.

A colleague, Helen Gibb alerted the Animal Health and Veterinary Laboratory Agency to a possible case of SBV last month. The shepherd, who has 200 early lambing ewes, had seen several lambs born with deformed limbs and told his vet.

Samples were sent to the AHVLA’s Bury St Edmunds centre for detailed analysis at Weybridge against the reference samples from Europe.

All cases in England to date have involved sheep flocks although SBV disease, which was identified in November last year in calves in northern Germany, hence the name, infects ruminants, cattle and goats.

It has also been found in dairy and beef cattle in Germany. and 150 sheep flocks. In Holland and Belgium, ewes seem to be susceptible and deformed lambs have been born but not survived. In Holland, two-thirds of sheep tested for SBV were positive.

It has also been found in France as far as Caen in Normandy, which indicates that flocks on the south coast could have been infected.

This virus seems to be spread by midges. It is likely the mild and warm conditions early last autumn enabled newly-pregnant ewes to be bitten.

Although vets cannot be certain, more evidence suggests that SBV does not infect all pregnant ewes.

A Westover partner, Tom Hume, said between 10 and 25pc of animals have been infected, which have produced deformed lambs.

It was difficult to build up a complete picture. He knew some ewes had produced a deformed (dead) lamb and a normal one. The live lamb and ewe were not found to SBV infected. This is quite different from bluetongue virus, where animals were “infected” and capable of spreading infection if later bitten by a midge, which then infected another sheep.

Mortality may be higher because a deformed lamb could block the birth canal, thus prevent other live births.

The human health risk is deemed as very low but farmers are advised to report symptoms to their vet although it is not notifiable.

SBV, which has been under investigation since August last year, can reduce yields and cause fever and diarrhoea in cattle.

The virus is a completely different type from Blue Tongue.