Copied from wayfinder, as I couldn't put it better myself.

As you will no doubt be aware, there have been a number of both reported and confirmed cases of Foot and Mouth disease recently. Additionally, since 22 September there have been cases of Blue Tongue Disease identified. Wayfinder would advise all users of the countryside to exercise extreme caution and understanding when enjoying our hobby. Please stay away from all rights of way in the areas affected by either of these very devestating diseases and also to be sensitive in other ares.

Be aware that landowners may understandably be aprehensive about the use of rights of way crossing or adjacent to their land even if they are not in an affected area. They have no way to know that the user of the way has not been in an affected area in the recent past.

Further information is available from DEFRA (Department of Environment, Food and Rural Affairs). The information on their website is updated regularly and you should check the current situation regularly using the links below:

http://www.defra.gov.uk/

http://www.defra.gov.uk/footandmouth/