A KILLER parasite that thrives in wet conditions is wreaking havoc among Cumbrian sheep flocks.

Vets warn that the Fasciola Hepatica para-site, which causes potentially fatal liver fluke, could continue to infect livestock ‘well into 2013’.

“The prolonged mild weather this winter has allowed the life cycle of of the Fasciola Hepatica to continue where it would usually cease,” South Lakeland vet Rachael Robertson said.

“The parasite and the tiny mud snail it lives in usually go into hiber-nation at this time of year, but the wet and relatively warm conditions have allowed it to build up on pasture where it becomes ingested by grazing sheep.

“Once inside its new host, the parasite passes through the sheep’s liver where it causes damage.”

David Clarke, who farms around 600 ewes and 1,000 lambs at Tullithwaite Hall, Und-erbarrow, said he had lost around 50 sheep so far this winter — far more than any previous year.

“You know when a sheep has become infected when you’re gathering them up and one suddenly stops runn-ing,” he said. “The sheep with liver fluke have no energy. An early way of telling is if you check the animal’s eyes and they’re white.”

The parasite infects both sheep and cattle but cattle seem to be more tolerant, said Mr Clarke. “The continuing wet weather is bad enough for livestock but liver fluke has made it worse. And it’s not cheap to treat. I’ve spent between £2,000 and £3,000 on treatment.”

Miss Robertson, who works at Kirkby Lonsdale-based Westmorland Farm Vets, added: “Our practice covers a large area from Morecambe Bay, Settle, Tebay and Grasmere and we’re seeing liver fluke in all areas.”

The practice is holding a free advice workshop on liver fluke on Thursday, January 10, at The Olde Mill, Bardsea, from 7.30pm. Call 01539 722692 to reserve a free place.