Diarrheagenicity of Sarcocystis Fayeri in Rabbits

Abstract

Whether or not Sarcocystis fayeri sarcocysts induces diarrhea was investigated via oral inoculation of bradyzoites into rabbits. When inoculated with 5.5×10⁶ bradyzoites, the rabbits had loose stool with some clinical signs including anorexia and depression. The rabbits receiving 1.5×10⁷ and 5.5×10⁷ bradyzoites showed watery stool. All of the latter died within 48 hours. Groups of the rabbits given 1.5×10⁷ bradyzoites were sacrificed one, two, three, six and nine hours after inoculation for histopathological analysis over time. The rabbits did not show any clinical signs and pathological changes until two hours later. By three hours post-inoculation, the rabbits revealed some clinical signs of anorexia, lost drinking behavior and depression that lasted until nine hours. Upon histopathological examination, apoptosis and desquamation of epithelial cells were found in the small intestine of the rabbits sacrificed at three to nine hours post-inoculation. The rabbits examined at six and nine hours also showed moderate to severe atrophy of villi as well as circumferential edema of submucosa. Diarrhea appeared only after a period of nine hours. These results suggest that S. fayeri sarcocysts induced diarrhea subsequent to acute damage of the intestinal mucosa in the rabbit.