Clinical Features:
Many infections are asymptomatic.  Acute schistosomiasis (Katayama's fever) may occur weeks after the initial infection, especially by S. mansoni and S. japonicum.  Manifestations include fever, cough, abdominal pain, diarrhea, hepatospenomegaly, and eosinophilia.  Occasionally central nervous system lesions occur: cerebral granulomatous disease may be caused by ectopic S. japonicum eggs in the brain, and granulomatous lesions around ectopic eggs in the spinal cord from S. mansoni, and S. haematobium infections may result in a transverse myelitis with flaccid paraplegia.  Continuing infection may cause granulomatous reactions and fibrosis in the affected organs, which may result in manifestations that include: colonic polyposis with bloody diarrhea (Schistosoma mansoni mostly); portal hypertension with hematemesis and splenomegaly (S. mansoni, S. japonicum, S. mansoni); cystitis and ureteritis (S. haematobium) with hematuria, which can progress to bladder cancer; pulmonary hypertension (S. mansoni, S. japonicum, more rarely S. haematobium); glomerulonephritis; and central nervous system lesions.

Laboratory Diagnosis:
Microscopic identification of eggs in stool or urine is the most practical method for diagnosis.  Stool examination should be performed when infection with S. mansoni or S. japonicum is suspected, and urine examination should be performed if S. haematobium is suspected.
Eggs can be present in the stool in infections with all Schistosoma species.  The examination can be performed on a simple smear (1 to 2 mg of fecal material).  Since eggs may be passed intermittently or in small amounts, their detection will be enhanced by repeated examinations and/or concentration procedures (such as the formalin-ethyl acetate technique).  In addition, for field surveys and investigational purposes, the egg output can be quantified by using the Kato-Katz technique (20 to 50 mg of fecal material) or the Ritchie technique.
Eggs can be found in the urine in infections with S. haematobium (recommended time for collection: between noon and 3 PM) and with S. japonicum.  Detection will be enhanced by centrifugation and examination of the sediment.  Quantification is possible by using filtration through a Nucleopore® membrane of a standard volume of urine followed by egg counts on the membrane.
Tissue biopsy (rectal biopsy for all species and biopsy of the bladder for S. haematobium) may demonstrate eggs when stool or urine examinations are negative.

Diagnostic findings

• Microscopy
• Antibody detection can be useful in both in clinical management (e.g., recent infections) and for epidemiologic surveys.
• Morphologic comparison with other intestinal parasites

Treatment:
Safe and effective drugs are available for the treatment of schistosomiasis.  The drug of choice is praziquantel for infections caused by all Schistosoma species.  Oxamniquine has been effective in treating infections caused by S. mansoni in some areas in which praziquantel is less effective.  See recommendations in The Medical Letter for complete information.