Schistosomiasis

Schistosomiasis is one of the most common parasitic infections in humans. Hepatic schistosomiasis is caused by Schistosoma mansoni, S. japonicum, S. mekongi, and S. intercalatum. Hepatic involvement by S. mansoni is particularly severe. The ova reach the liver through the portal vein and incite a chronic granulomatous reaction

Clinical presentation

The granulomatous reaction occludes the terminal portal vein branches, leading to;

ultrasound features

Widened echogenic portal tracts, sometimes reaching a thickness of 2cm. The porta hepatis is the region affected most. Initially the liver size is enlarged. As the periportal fibrosis progresses, however, the liver becomes contracted, and the features of portal hypertension prevail
The splenic veins may be enlarged and if there is portal hypertension, there is usually splenomegaly.
An increase in collateral circulation may develop around the splenic hilus and along the medial edge of the liver. This is seen as tortuos, echo-free structures which must be distinguished from fluid filled bowel
Periportal fibrosis may be either due to schistosoma mansoni or schistosoma japonicum

Periportal fibrosis due to s. mansoni — **Hepatic schistosomiasis.** Figure 1: *Transverse section of the left liver lobe showing fibrosis of the portal veins.* Figure 2 and Figure 3: *Image from the same patient showing dilatation of splenic vein multiple vericosites due to portal hypertension*

Splenic dilatation due hepatic schistosomiasis — **Hepatic schistosomiasis.** Figure 1: *Transverse section of the left liver lobe showing fibrosis of the portal veins.* Figure 2 and Figure 3: *Image from the same patient showing dilatation of splenic vein multiple vericosites due to portal hypertension*