FARMERS say the discovery of foot-and-mouth in previously uninfected areas is proof that the disease is far from under control.
The virus has reached the outskirts of Darlington, after a case was discovered at High House Farm, Brafferton.
This has led farmers to repeat the need for there to be minimum contact between farms in the region.
Richard Betton, Teesdale farmer and former chairman of North Riding and County Durham National Farmers' Union, said: "It is very worrying that the cases seem to be jumping to new areas, like Brafferton.
"The message from the Government is that it is coming under control and, although the number of cases appears to be dropping, we must not relax our guard.
"We need to be vigilant to stop it escalating again, and keep contact between different farms to an absolute minimum."
Mr Betton said he sympathised with High House's Tony Swinbank, who became the latest County Durham farmer to have a case confirmed.
He has lost 114 cattle and almost 500 sheep. Animals on five neighbouring farms have also been slaughtered, in continuing efforts to reduce the spread of the disease.
Mr Betton said: "It has had a devastating effect on farmers and I feel very sorry for everyone who has had animals destroyed.
"But we need to get through this so we can start rebuilding the rural economy."
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