Production of Tyzzer's disease in rats by ingestion of bacterial spores.

Tyzzer's disease was produced in rats by peroral inoculation with spores of Bacillus piliformis (Tyzzer's organism) of rat origin. After ingestion of 10(6) spores necrotized lesions with intracellular bacterial propagation were seen in the intestines, liver and heart on days 2 to 14 postinoculation (p.i.). A number of B. piliformis were present within enterocytes of the cecum and colon. Infected cells were also seen in the liver, myocardium and intestinal muscle layers on days 3 to 7 p.i. Infective spores were found to be shed in feces during 3 to 10 days p.i.