Devon and Cornwall have the most cases of the deadly Schmallenberg virus in the country.
The disease causes birth defects and miscarriages in livestock. Latest figures show that Devon had 185 cases and Cornwall 96 by the end of March. Other badly affected areas are Dorset and South Somerset.
Sheep farmers are at crisis point. They say recent bad weather, low supermarket prices and now the return of the deadly Schmallenberg virus are threatening to put them out of business.
Schmallenberg causes birth defects in lambs. And while it was only discovered a year ago, farmers say the impact has been huge - 91 cases have been confirmed across Dorset and Somerset so far this year.
One farmer says if his sheep contract the virus his livelihood will be destroyed.
Tanya Mercer reports:
As sheep farmers in the region experience higher than normal losses, still births and deformities, the NFU says every effort must be made to ensure a vaccine is available later this year to help combat the spread of the deadly Schmallenberg virus.
The disease has spread across England and Wales to the Scottish border region, and has now been confirmed on more than 1,000 UK farms.
Although it is still being recognised by Defra and the European Commission as 'low impact' on a national scale, the cost for individual businesses can run into thousands of pounds.
It comes at the same time as lamb prices have hit their lowest level for three years and livestock producers are facing rising production costs due to the extreme weather in 2012.
The National Farmers' Union says it's vital that a vaccine for Schmallenberg virus is made available this year. The disease causes stillbirths and birth defects in sheep and cattle and is carried through insects.
It's spreading through the South West, with nearly 60 cases in Dorset and more than 50 in South Somerset.
A disease that causes birth defects in sheep and cattle is spreading. Cases of the Schmallenberg virus have already been reported in Cornwall. It's now been found in Devon, Dorset and Somerset.
The Schmallenberg virus can lead to stillbirths and deformities in sheep, goats, and cattle. It's now been identified at farms in Wiltshire, Gloucestershire & Cornwall who each have one confirmed case linked to sheep. 83 cases of the disease have been recorded throughout the country. Find out more.