Accepted
at 12:21 a.m. Nov, 01, 2023
by
dollajas
Author:
shmuelsash
Type of change:
Other
Rationale for change
clarify cloze
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Dissemination depends on which species
Lecture Notes
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Missed Questions
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Pathoma
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Boards and Beyond
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First Aid
Sketchy
Sketchy 2
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Sketchy Extra
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Picmonic
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Pixorize
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Physeo
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OME
Additional Resources
Life cycle of schistosomes
An infected human, the definitive host of schistosomes, excretes schistosome eggs in urine or feces (yellow and brown arrow). The eggs hatch in water and release miracidia. These flat, ciliated larva penetrate specific freshwater snails, which then act as intermediate hosts. In the snail, the miracidia develop into sporocysts, which reproduce asexually to form cercaria. Cercaria are then released back in the water. When humans come in contact with contaminated water, cercaria can penetrate the skin and enter the circulation. As they lose their tail, the cercaria develop into schistosomula, which then mature into adult schistosomes in the venous system. At this point, a male and female adult worm mate and migrate to the veins of the target organs (liver, intestine, bladder). The female worm lies folded in the longitudinal cleft (schist) of the male worm and lays eggs, which causes inflammation of the organs. As a result of the inflammation, the eggs can penetrate the wall of the organ and enter the lumen of the intestine or bladder (depending on the species), and they are then eliminated in feces or urine.
One by one
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