Classification of lesions observed cases of paratuberculosis in natural goats

Sixty-eight adult goats with clinical or sub-clinical paratuberculosis, fro m naturally infected flocks, were subjected Post mortem to a pathological e xamination that focused on the intestinal lymphoid tissue. The lesions were divided into four categories. Focal lesions, found in 16 goats, consisted of small granulomata in the ileocaecal Peyer's patches or related lamina pr opria. Diffuse multibacillary lesions (34 goats) consisted of a granulomato us enteritis, affecting different intestinal sites. Numerous macrophages co ntaining many mycobacteria were present, resulting in macroscopical changes in the normal gut morphology; in the ileum of nine of the 34 animals, howe ver, these changes were confined to the apex of the villi and the intestina l wall was not thickened. In diffuse lymphocytic lesions (10 goats), the ly mphocyte was the main inflammatory cell, with some macrophages (containing few if any mycobacteria). In diffuse mixed lesions (eight goats) the infilt rate consisted of numerous lymphocytes and macrophages, with small numbers of mycobacteria. The three types of diffuse lesion were often associated wi th. necrosis in the lymph vessels of the mucosa, mesentery and lymph nodes, and with greater thickening of the jejunum than of the ileum. Mycobacteriu m avium subspecies paratuberculosis was cultured from 69% of goats with dif fuse lesions and from 44.4% of those with focal lesions. (C) 2000 Harcourt Publishers Ltd.