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Schistosomes - Essay Example
Schistosomiasis, or bilharzia is a parasitic disease caused by trematodes of the genus schistosoma and is considered by the world health organization as the second most important disease only to malaria, infecting hundreds of millions globally. Schistosomes themselves are as intriguing as the disease itself, exhibiting attributes that are unique to the genus (Combes 1991)…
This article essays the implication of this unique physiological characteristic and its consequences on schistosome life history particularly their faithfulness while choosing a mate.
Adult schistosoma lives in the mammalian blood but their life cycle requires a phase of asexual reproduction within a secondary host. The life history of the parasite begins when adult female deposit eggs in the veins surrounding intestine or bladder. The mammal then continues the life cycle by transmitting those eggs through urine or feces. Once in water, the eggs hatch into marcidia, which must find an appropriate snail host. Once inside the snail each marcidium produce several hundreds of carcariea which when released in water seeks the skin of suitable mammals to burrow into. There are many different species of schistosomes of which Schistosoma haematobium, S. mansoni, and S. japonicum clinically important parasites that infect humans. Schistosoma haematobium , commonly called urinary schistosomiasis, dwells in the vesical veins surrounding the urinary tract and therefore mammal host usually excretes its eggs in urine. It is found throughout most of Africa and in parts of Western Asia. Two species, S. mansoni and S. japonicum cause intestinal schistosomiasis. S. mansoni usually occupies the mesenteric veins around the large intestine,while S. ...