EN
Composition of the bacterial flora accompanying Balantidium coli in the rectum content of pigs affected by acute (Group 1) and symptom-free (Group 2) balantidiosis was studied. The course of balantidiosis was found to be dependent on composition of the bacterial flora. B. coli virulence towards the host’s tissues may be a secondary effect of the changes in biological, chemical, and physical conditions of the parasite’s biotope.