THE SMALL-INTESTINE IN EXPERIMENTAL GIARDIASIS OF RATS - MORPHOLOGICAL-CHANGES AND MAST-CELL RESPONSE

Three-week old rats were orally infected with 10.000 Giardia muris cysts. The elimination of the parasite and the histological changes in the jejunum were studied for an observation period of 56 days. During the whole period the parasites could be observed in an intraluminar position in the jejunum (trophozoites) and in the feces (cysts). The morphological changes in the jejunum were only minor, consisting in a transient change in villus-crypt ratio, goblet cell increase, focal infiltration with lymphocyte like cells and plasma cells. Of particular interest was the proliferation of mucosal mast cells observed from 28 to 56 days post infection. It was concluded that the rat might serve as a model for longstanding Giardia infections accompanied by minor pathological changes in the gut and proliferation of mucosal mast cells. In addition to the well documented mucosal mast cell proliferation during a helminth infection, this study indicates that also a protozoan parasite is capable of inducing a mucosal mast cell response.