Schistosoma mansoni
is a multicellular parasite commonly called the "blood fluke". Schistosoma infection may be contracted when fresh water organisms penetrate intact skin. They are then carried in the bloodstream to the liver or urinary bladder where they mature into an adult. If both male and female are present, fertilization occurs, ova are produced and shed in the feces. Upon contact with water, the ova release a ciliated larval form called a miracidium. The miracidium enter certain species of snails. Maturation in the snail results in a free-swimming form (cercaria) which may penetrate intact human skin and infection ensues.
Because Schistosoma have separate male and female organisms, they are "dioecious" . Image 1 shows male and female adult Schistosoma mating within intestinal blood vessels. Mating results in the production of ova which are shed in human feces and are used for diagnosis.
Because the adult Schistosoma is flat in shape, it is in the phylum Platyhelminthes and the class Trematoda(flukes). Trematodes are parasites that have a simple digestive tract and at least one intermediate molluscan host (in this case a snail).
Click on each image to see the enlarged version.
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| 1. adult 20 X | 2. ova 400 X | 3. ova 400 X | 4. ova 400 X | 5. ova 400 X |
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| 6. ova 400 X | 7. ova 400 X | 8. ova 400 X | 9. ova 400 X | 10. ova 400 X |
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