Foot and mouth disease. Sign by a footpath asking walkers to take precautions against the spread of foot and mouth disease. This disease, caused by viruses in the picornavirus group, infects domestic and wild cloven-hooved animals, causing a fever and the development of blisters in the mouth and on the feet. It is highly contagious, spreading through contact with infected animals and products, in the air and on equipment exposed to infection. Animal and human movement restrictions help limit the spread of the disease from infected farm animals. Photographed in Norfolk, England, in 2001.