Schistosomiasis
Michael W. Peterson, DO
Cary Chisholm, MD
Clay J. Cockerell, MD
Key Facts
Terminology
Schistosomes are trematodes (flukes) or flatworms
Etiology/Pathogenesis
Schistosomes &/or their eggs lodge in vessels
Clinical Issues
Sudden widespread eruption of red urticarial pruritic papules on uncovered or exposed skin
Subsides and recurs for several days
Some cercariae (S. japonicum) that lodge into skin can cause severe urticarial eruption
Microscopic Pathology
Epidermal spongiosis and dermal edema
Mixed inflammatory infiltrate of predominately neutrophils with a few eosinophils
Dermis may contain ova or worms with associated granulomatous reaction
 Clinical photograph shows schistosomiasis of the labia majora presenting as swelling  that mimics warts. (Courtesy M. Ramos-e-Silva MD, PhD.) |
 Histopathology of schistosomiasis of the vulva demonstrates a single oval egg  amid a chronic inflammatory infiltrate. (Courtesy M. Ramos-e-Silva MD, PhD.) |
TERMINOLOGY
Synonyms
Bilharziasis, cercarial dermatitis, swimmer’s itch (fresh water), clam-digger’s itch (salt water)
Definitions
Schistosomes are trematodes (flukes) or flatworms
3 common species
Schistosoma haematobium: Infects urinary system
S. japonicum: Primarily infects liver
S. mansoni: Infects intestines
Other schistosomes can penetrate skin
Cannot survive in humans
Causes temporary cercarial dermatitis
ETIOLOGY/PATHOGENESIS
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