Schistosome

• GeneralThe bilharzia it causes affects over 200 million people.
• Unlike almost all flatworms, it has separate sexes and forms permanent pairs: the broader male houses the female for life in a fold of his body called the gynaecophoric canal.
• Its larvae pass straight through the skin of anyone entering infested fresh water, without having to be swallowed.
• Its cycle depends on snails of the genus Biomphalaria, and controlling the disease means managing the snails and access to water as much as treating people.
• Schistosomes are exceptional among flukes in having separate sexes and living in a permanent pair: the broader male houses the female in a fold of his body called the gynaecophoric canal, where she stays for life.
• You do not have to drink the water to be infected: the larva penetrates the intact skin of anyone bathing, washing clothes or wading in contaminated fresh water.
• The damage is caused not by the worm but by the eggs. Those trapped in the liver provoke an inflammatory reaction that ends in fibrosis and portal hypertension.
• Schistosomiasis affects more than 200 million people and is, after malaria, the parasitic disease with the greatest socio-economic impact in the world.
• It is treated with praziquantel, and control depends on sanitation and on reducing the populations of host snails.

Skeleton type

Invertebrate - no rigid skeleton (hydrostatic skeleton)

Habitat and environment

A parasite: the veins of the abdomen; canals and lakes with snails

Sources consulted: Wikipedia (es): Schistosoma mansoni