Schistosoma mansoni hepatic fibrosis in Syrian golden hamsters: effect of dose and duration of infection as shown by immunohistopathological studies.

: In this work, 180 Syrian golden hamsters were infected with Schistosoma mansoni and 30 cross matched for age and sex served as control. Infected hamsters were divided into six main groups according to the number of infected cercariae (20, 50, 100, 150, 200 and 250 cercariae). Each group was sub-divided into 5 subgroups, according to the duration of infection after which animals were sacrificed (4, 6, 8, 12 and 24 weeks). Control and infected hamsters were subjected to laboratory evaluation of serum albumin, S. globulin and A/G ratio and histopathological examination of the liver and splenic tissues. A significant reduction of albumin was observed in Schistosma infected hamster (50 cercariae or more) but not in the control ones and those infected with 20 cercariae. There was a significant correlation between these changes and the duration of infection and the number of adult worms recovered from the mesenteric circulation at the end of the experiments. Histopathologic evaluation showed appearance of the circulating schistosome antigens, circulating anodic antigen (CAA), and circulating cathodic antigen (CCA) deposits in the liver by the 14th week after infection; liver granuloma, amyloid deposits, fibrosis, Schistosma pigments as well as inflammatory infiltration was observed at 8-12th week and amyloid deposits, CAA & CCA in the spleen was observed nearly at the same time.