Snapshot A 29-year-old woman presents to the emergency department with 2 weeks of fever and abdominal pain. She denies any sick contacts but did recently return from Kenya. Physical examination is notable for hepatomegaly, most prominent in the left hepatic lobe. She also has an urticarial rash in her left foot. Urine and stool microscopy are remarkable for schistosome eggs and a complete blood cell count demonstrates eosinophilia. Introduction Definition human infection caused by the Schistosoma trematode Microbiology the 3 major species that cause disease are Schistosoma mansoni (Africa and South America) causes intestinal tract and hepatosplenic disease S. haematobium (Africa and Middle East) causes genitourinary tract disease S. japonicum (East Asia) causes intestinal tract and hepatosplenic disease Associated conditions squamous cell bladder cancer (S. haematobium) portal hypertension (S. mansoni and S. japonicum) Epidemiology Incidence most cases occur in sub-Saharan Africa ETIOLOGY Pathogenesis female trematode lays eggs in the patient's capillaries → traverses the blood vessels and migrates to the intestines (S. mansoni and S. japonicum) or the bladder (S. haematobium) → causes an immune response leading to inflammation and fibrosis Presentation Symptoms pruritus after swimming ("swimmer's itch") suggestive of larval penetration fever chills myalgias and arthralgias headache abdominal pain Physical exam urticaria angioedema hepatomegaly hematuria Studies Microscopy schistosome eggs identified on microscopic exam of urine or stool confirms the diagnosis Serology indication if microscopy is unremarkable tests ELISA radioimmunoassay comments typically negative in acute infection Labs eosinophilia Differential Malaria differentiating factor trophozoite ring within red blood cells in the peripheral blood smear Treatment Medical praziquantel indication treatment of choice for schistosomiasis Complications Squamous cell carcinoma of the bladder Portal hypertension Prognosis Treatment may decrease organ pathology