[Parasitic diseases of the liver]

The liver seems to be very attractive for many parasites which may either inhabit the organ or pass through during their normal development or may be carried to the liver leading to destruction there. Malaria parasites have a short developmental stage in the hepatocytes, but they do not damage the organ. For the leishmanias (Leishmania donovani complex) are the Kupffer cells are the target cells causing visceral leishmaniasis or kala azar. Nematodes of the ascarid group have a special affinity for the liver. The larvae of the human Ascaris have to pass through the parenchyma once during their developmental cycle, the larvae of animal ascarids on the contrary migrate within the liver for longer periods of time. Eggs of the schistosomes are carried via the portal system into the liver and trapped there in the tissue. An inflammatory granuloma develops around them. If the egg load is high, fibrosis of the liver may finally develop leading to portal hypertension. While small liver flukes (Clonorchis, Opisthorchis) living in the bile ducts do little harm to the liver in most cases, the larger liver fluke Fasciola hepatica destroys liver tissue during an early migratory phase of several weeks duration. Larval cestodes of the genus Echinococcus are usually found in the liver as closed cysts growing by expansion (E. granulosus) or as more solid structures growing by infiltration and destruction (E. multilocularis). Destruction results also if ameba (Entamoeba histolytica) invade the liver. Large areas of necrosis, liver abcesses are formed.