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, hepatosplenomegaly, 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.
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
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®
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.
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