Transformation of warts to malignancy in alimentary carcinoma in cattle.

There is a high incidence of alimentary carcinoma in beef cattle in the highland areas of Britain. Evidence is presented to shown that this is associated with the presence of bracken fern on high incidence farms and that many of the carcinomas arise in pre-existing virus-induced papillomas. Papillomas are much commoner and occur in greater numbers in animals of all ages on the cancer farms as compared to lowland cattle. Papillomas are found in all ages of cattle; carcinomas have only been seen in cows over 6 years of age. The virus has been isolated, visualized and purified; it produces papillomas when inoculated into the alimentary tract and skin.