RESUMO
Histopathological changes in intestinal and hepatic amoebiasis were studied in Swiss albine mice with and without silica pretreatment. The intestinal infection rate was higher in silica treated mice (83%) as compared to non-silica treated mice (33%). Histologically all the silica treated mice had caecal ulceration which tended to spread across the muscularis propria into the serosal layer. The hepatic lesions were observed grossly in 100 and 60 per cent mice with and without silica treatment, respectively. However, the liver lesions in the silica treated mice were more severe, leading to satellite abscesses and in some cases the capsule ruptured leading to adhesions to the diaphragm and peritoneum. Histologically, the blockade of histiocytes with silica resulted in mainly a neutrophilic damage which was extensive and widespread. It also destroyed the amoeba and led to abundant fibrosis. In the non-silica group the damage was slow and devoid of neutrophils with quicker healing and lack of fibrosis resembling human hepatic lesions.