The virus replicates primarily in the upper respiratory tract, tonsils, or upper alimentary tract and there is '''aerosol''' excretion during this incubation period. This is then followed by a viremia. Virus targets stratum spinosum of stratified squamous epithelia and mucus membranes and secondary '''vesicles''' appear after incubation of 2-14 days. Lesions also affect the feet with cutaneous erosions in interdigital cleft, at coronet and bulbs of heals . These feet lesions often take a long time to heal as secondary bacterial infections may ensue and produce true deep ulcerative dermatitis. In the young, without maternal antibody, virus will localize in the heart, particularly the wall of the left ventricle, resulting in multi-focal necrosis of the myocardium and subsequent death. Persistent infection of cattle can occur in unkeratinized lesions, but subclinical carriers do not usually transfer infection except for subclinical buffalo that can transmit the disease. | The virus replicates primarily in the upper respiratory tract, tonsils, or upper alimentary tract and there is '''aerosol''' excretion during this incubation period. This is then followed by a viremia. Virus targets stratum spinosum of stratified squamous epithelia and mucus membranes and secondary '''vesicles''' appear after incubation of 2-14 days. Lesions also affect the feet with cutaneous erosions in interdigital cleft, at coronet and bulbs of heals . These feet lesions often take a long time to heal as secondary bacterial infections may ensue and produce true deep ulcerative dermatitis. In the young, without maternal antibody, virus will localize in the heart, particularly the wall of the left ventricle, resulting in multi-focal necrosis of the myocardium and subsequent death. Persistent infection of cattle can occur in unkeratinized lesions, but subclinical carriers do not usually transfer infection except for subclinical buffalo that can transmit the disease. |