Validation of ultrasonography for hepatic schistosomiasis using a porcine Schistosoma japonicum model

Ultrasonography is increasingly used to record hepatosplenic involvement in schistosomiasis. However, questions remain unsolved regarding diagnostic accuracy in mild hepatic disease and under influence of confounders like co-infections. We report on a study to evaluate the suitability of a pig model of schistosomiasis japonica to investigate such problems. Nine pigs (12 weeks of age) were infected with 1000 Schistosoma japonicum cercariae. Together with 10 uninfected controls, they underwent B-mode and Doppler ultrasonography 12 weeks after infection, followed by parasitological and gross pathological examination and quantification of hepatic collagen. At this time, all infected pigs had patent infection, hepatic displacement of ova and various grades of portal and septal liver fibrosis. Sonographically, echogenic portal thickening (ePT), increased hepatic echogenicity (EG), increased hepatic dimensions and dilatation of the portal vein were found to correlate with other parameters of morbidity. Algorithms from human medicine were appropriate to grade ePT in the pig model. It is concluded that the porcine model of schistosomiasis japonica can be instrumental in approaching problems which for any reasons cannot be studied in human beings.