Granulomatous-like immune reaction and hepatic fibrosis induced by Schistosoma haematobium immature worms.

Golden hamsters were inoculated with Schistosoma haematobium cercariae to examine histological lesions at different time points over an 18 month period of infection. Hamsters were sacrificed 26 weeks and 82 weeks after inoculation. The parasite was found in the blood and in the liver of infected animals as was expected, but we found exclusively male worms, no female worms nor eggs. Interestingly we observed unexpected hepatic lesions induced by S. haematobium adult male worms alone in the golden hamster, characteristic of schistosome eggs. Samples from liver, kidneys, lungs, bladder and gastrointestinal tract were collected during necropsy to evaluate injuries induced by S. haematobium. Notably we observed hepatitis in the liver of infected hamsters, no lesions were found in other organs. We also found liver fibrosis in infected hamsters. This study provides further experimental evidence for the role that schistosome worms, and their derived antigens, may play in the pathology of the infection and modulation of liver chronic inflammation in the murine model of schistosomiasis.