Effects of intestinal protozoa infection on gastrointestinal transit and contractility in experimental animals

Three groups of animals each was orally infected with Cryptosporidia parvum oocysts, Enterocytozoon bieneusi spores or Cyclospora cayetanensis oocysts. At the time peak of colonization of infected animals, each group and its corresponding control were infused orally with radioactive isotope. Gastric emptying of isotope was significantly greater in infected compared to controls in both fasted and fed states, to determine the effect of each parasite on the contractility of longitudinal and circular muscle, isometric tension of jejunal segments was recorded. The development of active tension with stretch and the dose-response curve to muscarinic against were significantly increased in the longitudinal muscle of infected animals compared to controls. The circular smooth muscle did not show an increase in contractility. The results suggest that an altered gastrointestinal transit and smooth muscle contractility may be involved in the intestinal protozoa infections' pathophysiology.