Anatomic Pathology: Infectious Disease Pathology

1043) What organism is shown in the image?

• Schistosomiasis is a parasitic disease caused by Schistosoma spp. and is acquired by swimming in water contaminated by infected snails (intermediate hosts). Schistosoma cercaria penetrate human skin and circulate through various tissues finally to mature to adult worms in venules. Eggs of different species can be differentiated by their location (urine and bladder versus feces and intestines), size, and morphologic appearance.

S. mansoni and S. japonicum are most commonly found in venules of the mesenteric plexus of the large and small bowel, respectively.

S. haematobium is most commonly identified in venules of the venous plexus of the urinary bladder and rectum.

S. mansoni infection causes obstruction of portal blood flow resulting in portal hypertension and cirrhosis.

S. haematobium infection causes chronic cystitis and ureteritis, which can progress to malignancy.

S. mansoni and S. japonicum can lodge in pulmonary venules and cause pulmonary hypertension.

Chitsulo L, Loverde P, Engels D: Schistosomiasis. Nat Rev Microbiol 2004;2(1):12-13.

Fried B, Reddy A, Mayer D: Helminths in human carcinogenesis. Cancer Lett 2011;305(2):239-249.

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