Intragastric infection of conventional and germfree mice with Giardia lamblia
Torres, M.R.; Silva, M.E.; Vieira, E.C.; Bambirra, E.A.; Sogayar, M.I.; Pena, F.J.; Nicoli, J.R.
Brazilian Journal of Medical and Biological Research 25(4): 349-352
1992
ISSN/ISBN: 0100-879X PMID: 1342210 Document Number: 390536
The effects of experimental infection with G. lamblia [G. duodenalis] were studied in 30-day-old conventional and germfree CFW mice (7 animals in each group) of both sexes. Cysts were observed in the faeces of both groups 6 to 7 days after ig inoculation of each animal with about 2.5 x 105 G. lamblia trophozoites. Faecal cyst level was statistically higher in germfree mice (about 105 cysts/g faeces) when compared with the conventional group (about 104 cysts/g faeces). The peak of infection in the conventional group apparently occurred on day 10 pi as indicated by an increase of faecal weight and by histopathological examination. Intense infiltration of the lamina propria and high reactional hyperplasia of the lymphoid component were observed in the conventional group. There was no infiltration or hyperplasia in germfree infected mice and faecal weight was relatively constant throughout the experiment. These results suggest that, as is the case for other intestinal pathogenic protozoa, the intestinal microflora is indispensable for the expression of the pathogenicity but not for the multiplication of G. lamblia.