A deadly livestock disease could wipe out half the lambs in Sussex this spring, an expert has claimed.

The county is the worst hit area in the UK by the Schmallenberg virus, which leaves newborn lambs dead or deformed.

Six more Sussex sheep farms have reported the disease since Monday, with 24 in total now affected as well as one cattle farm.

Sally Clay, who is hired by farmers to deliver their newborn lambs, fears the number of cases could rise rapidly as the lambing season starts in earnest.

She said: “It’s definitely going to be a lot bigger than we thought because a lot of farmers haven’t even started lambing yet.

“I just did a flock where around 10% of lambs were deformed, but I fear it could get much worse.

“I think farmers could end up losing up to half of their lamb crop. The price of lamb has been on the increase and things were looking good – but this is just another blow.”

The Schmallenberg virus is thought to be spread by midges, mosquitoes and ticks and causes birth defects, stillbirths and miscarriages.

More damage is done to the unborn lamb if the disease is contracted by the mother early in the pregnancy, experts believe.

If this is the case, many ewes who could have been exposed to the virus at the end of last year could be heading into the lambing season carrying deformed young.

However, farmers do not know if their animals have been affected until they give birth.

Last month, Martin Carr found the virus on his sheep farm near Rottingdean.

He said the new disease could spell financial disaster for many farmers.

“There’s so little known about the virus that it’s very difficult to know what to do about it,” he said.

“We are very worried because we don’t know how serious this could be. We are all farming in the dark and there’s nothing that we can do.”

A spokesman from Defra said: “We don’t want to play down the impact of the disease, which is really worrying for the farmers involved, but so far it has had a relatively limited impact.

“But of course, this could change as the lambing and calving seasons continue.

“Animal to human transmission currently looks very unlikely and assessments by health authorities both here and in Europe show that it is very unlikely the disease will affect humans.

“We believe midges spread the disease from Europe late last year, but as it affects newborns we are only now able to see where it is occurring.”