Invasion of small intestinal mucosa by Giardia lamblia in man.

The mucosal biopsies from duodenum and jejunum of 31 patients showing Giardia lamblia in their feces were studied histologically. Although the trophozoites were found in all the biopsy specimens in the luman, the tissue invasion by the parasites in different stages, from their entry through the epithelium to the lamina propria could be demonstrated in 12 of them, all of the latter having diarrhea and steaterrhea. Varying histological changes in jejunal mucosa were also observed in 9 cases, of which 7 showed mucosal invasion by giardia trophozoites. In 17 of the series neither tissue invasion by the parasite nor mucosal change could be found.