Trematode - Schistosomas Images

Schistosomes: Blood Flukes Schistosoma japonicum and Schistosoma mansoni* cause intestinal schistosomiasis.

• Acute form manifests as Katayama fever, which is characterized by gastrointestinal symptoms, pain, cough, enlargement of the spleen and/or liver, and eosinophilia.
• If infection is chronic, granulomas can form around the eggs.

– Fibrosis, called Symmer's pipe stem peri-portal fibrosis (aka, clay pipe fibrosis) can lead to tissue destruction and portal hypertension. – Granulomas can also form in other tissues, including the central nervous system. Schistosoma haematobium* causes urinary schistosomiasis, also known as vesicular schistosomiasis.

• Hematuria, scarring, and calcification.
• Associated with urinary bladder cancer.

Be aware that trematodes have multiple larval stages with unique forms and names; for simplicity, we'll just refer to each of these forms as "larvae." – More detailed version. 1. Free-living larvae called miracidia invade snails (the intermediate hosts) and give rise to cercariae larvae. 2. Cercariae exit the snail to seek their next host. 3. Upon contact with a human, the parasites penetrate the skin and lose their tails, transform to the schistosomulae form. 4. Schistosomulae travel to portal veins. 5. The parasite matures to its adult form in the portal blood – Schistosomas have separate sexes: the male is larger, and the "threadlike" female resides in his gynecophoric canal. 6. Paired Schistosomes migrate and lay eggs: – Schistosoma japonicum and Schistosoma mansoni tend to lay eggs in the mesenteric veins, which causes intestinal schistosomiasis. – Schistosoma haematobium tends to lay eggs in the urinary venous plexus, which causes urinary schistosomiasis. 7. Eggs are excreted in the feces or urine, depending on their location. 8. In the environment, the eggs hatch and give rise to the miracidia larval forms that will invade snails. – Be aware that not all eggs are excreted, but, instead, can become encased in inflammatory granulomas as described above. Image Credits: https://commons.wikimedia.org/wiki/File:Cerebral_schistosomiasis.jpg https://www.cdc.gov/dpdx/schistosomiasis/index.html http://www.publicdomainfiles.com/show_file.php?id=13392942171752 https://www.cdc.gov/dpdx/schistosomiasis/index.html