Hepatosplenic schistosomiasis: a model for the study of portal hypertension** This text corresponds to the State of the Art Lecture given in Fukuoka, Japan, during the Biennial Meeting of IASL in 2000

Annals of hepatologySchistosomiasis is an endemic disease of tropical areas.In American countries as Brazil, Venezuela, Puerto Rico, Antilles and Suriname the worm that causes schitosomiasis is the schistosoma mansoni.According to the World Health Orzganization more than 600 million people live in risk areas and about 200 million are infected in 75 countries.1 The biological cicle of the worm corresponds to three phases: when human feces containing the eggs of the parasite fall in water, they rupture liberating the miracide.The intermediate cicle occurs in a snail of the gender biomphalaria.The parasite multiplies inside the snail and after 20 to 30 days gives origin to the cercariae, that spread in warm water of about 20 to 25 degrees Celsius.Free in the water the cercariae enter through the intact skin and mucosa, suffering modifications and achieving maturation in the portal system, where sexuated adult worms lay their eggs.From the portal system eggs can spread to tissues and organs, specially the liver and intestines.As eggs are elimianted with feces they may contaminate water, closing the cycle.Adults worms live in the portal system, where about 300 eggs per day are laid and about 2/3 of them carried to the liver.The typical egg has a characteristic lateral spine, useful for its diagnosis, not only in stools but also in the various tissues where the egg can be found (Figure 1).As various couples of adult worms can be found in the veins of the portal system, specially the mesenteric veins, this parasitic infection gives rise to a vascular disorder that may end up with an hepatic disease.Worms and eggs are responsible for the pathopysiology of the disease.In the initial phases there is formation of immune complexes, rarely with acute manifestations.The chronic forms are very common, due primarily to the deposition of eggs and dead worms in different organs and tissues, particularly intestines and liver.In the later they obliterate small vessels, forming granulomas in the portal tract, obstructing

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