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The infectious stage starts when the free-swimming larval form of the schistosome, cercariae, penetrates the human skin using their suckers, proteolytic enzymes, and tail movements; the cercariae transformed into schistosomulae by losing its tail and subsequently travels to the heart and lungs through the venous system until it eventually ...
Schistosoma is a genus of trematodes, commonly known as blood flukes.They are parasitic flatworms responsible for a highly significant group of infections in humans termed schistosomiasis, which is considered by the World Health Organization to be the second-most socioeconomically devastating parasitic disease (after malaria), infecting millions worldwide.
Life cycle of S. haematobium. S. haematobium completes its life cycle in humans, as definitive hosts , and freshwater snails, as intermediate hosts, just like other schistosomes. But unlike other schistosomes that release eggs in the intestine, it releases its eggs in the urinary tract, which are excreted along with the urine. [ 15 ]
Schistosoma mansoni is a water-borne parasite of humans, and belongs to the group of blood flukes (Schistosoma). The adult lives in the blood vessels ( mesenteric veins ) near the human intestine. It causes intestinal schistosomiasis (similar to S. japonicum , S. mekongi , S. guineensis , and S. intercalatum ).
It has also shown that the spirorchiids are the closest relations of the schistosoma. An outline of the evolution of the schistosoma is now possible. The ancestral species infected freshwater turtles and the life cycle included gastropod hosts. Some of these species in their turn infected the marine turtles. [3]
Schistosoma intercalatum's life cycle is very similar to that of S. haematobium, except for some key differences. To start the life cycle, the human host releases eggs with its feces. In water, the eggs hatch to become miracidia, which penetrate the freshwater snail intermediate host. [5]
Schistosoma japonicum is an important parasite and one of the major infectious agents of schistosomiasis. This parasite has a very wide host range, infecting at least 31 species of wild mammals , including nine carnivores , 16 rodents , one primate (human), two insectivores and three artiodactyls and therefore it can be considered a true zoonosis .
The genera most commonly associated with swimmer's itch in humans are Trichobilharzia [4] and Gigantobilharzia. It can also be caused by schistosome parasites of non-avian vertebrates, such as Schistosomatium douthitti, which infects snails and rodents. Other taxa reported to cause the reaction include Bilharziella polonica and Schistosoma bovis.