[Further studies on the mongolian jird model of Giardia lamblia].

Seventy-seven Meriones unguiculatus were inoculated intra-esophageal with Giardia lamblia cysts isolated from the stool of a Giardia infected child. Correlation between oral dosage, course of infection, trophozoite distribution and the pathological changes in the small intestine of the infected jirds were studied. One (12.5%) of eight animals became infected with only 5 cysts. 10(4) cysts/jird or more was infective to nearly all the animals. Most of the infected animals (83%) excreted cysts and/or trophozoites intermittently. The extent of trophozoite colonization and their distribution in the small intestine varied with the time of infection, but not with the number of Giardia found in the feces. There was no direct correlation between the size of inoculum and the course of infection, the fecal output of cysts and/or trophozoites, or the intensity of pathological changes in the small intestine. The histopathological lesions induced by G. lamblia included cellular infiltration of the mucosa of the small bowel, nodular lymphoid hyperplasia, edema of the lamina propria and increase in mucous secretion. Necrobiosis and shedding of the epithelium was evident, and the mitotic figures of intestinal crypt increased significantly. The reduction of the villi to crypts ratio may indicate that the villi of small intestine were covered by relatively immature enterocytes, which may, partially, account for the malabsorption in giardiasis (Figs. 1-3).