Swine dysentery. Comparison of experimental diseases produced by infection with colonic mucosa or with Treponema hyodysenteriae, French strains, and of "natural" disease.

Oral inoculation of colonic mucosa scrapings and intestinal contents of animals affected with swine dysentery, or of pathogenic strains of Treponemia hyodysenteriae, as well as spontaneous contamination in infected pens caused in average swine dysentery to appear in 359 out of 409 SPF piglets. The morbidity is high irrespective of the method of contamination: after pen contamination, 75 out of 83 piglets were dysenteric; after only one ingestion of contaminated matter, 265 out of 280 animals were ill; and after inoculation of T. hyodysenteriae, 25 out of 35. Mortality in dysentery was always higher than 80%, respectively 48 out of 60 animals, 132 out of 154, and 13 out of 14. Very few animals were self-cured. The average incubation period varied according to the mode of contamination between 9 and 13 days. Animals having contracted an acute form of the disease died 16 to 23 days after contamination, and those with a chronic from 19 days, also after contamination. The increase in the number of Treponema, of Campylobacter and of Balantidium observed after the onset of the disease was approximately equivalent for all three modes of contamination. This disease was characterized by an alternance of dysentery stricto sensu and of mucoid diarrhea, the latter occurring more frequently in cases of self-cure and in chronic forms.