贾第虫长爪沙鼠动物模型某些问题的研究

FURTHER STUDIES ON THE MONGOLIAN JIRD MODEL OF GIARDIA LAMBLIA

以来自感染儿童贾第虫包囊感染长爪沙鼠的结果表明,5个包囊即可使12.5％的沙鼠受染。感染率随灌注包囊量增加而升高。10~4个包囊时,感染率可达100％。多数受染沙鼠呈间歇性排包囊。小肠中滋养体数及分布与病程有关,与粪便排虫量无对应关系。贾第虫不侵袭肠组织,但能引也小肠典型炎症改变,如绒毛上皮坏死脱落、肠腺细胞分裂相增加和绒毛长度/腺体长度比值下降。

Seventy-seven Meriones unguiculatus were inoculated imraesophageally 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 inustine of the infected jirds were studied. One (12.5%) of eight animals became infected with only 5 cysts. 104 cysts/jird or more was infective to nearly all the animais. Most of the infected animals (83%) excreted cysts and/or trophozoites intermittendy. 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 entero-cytes, which may, partially, account for the malabsorption in giardiasis (Figs. 1-3).