• Schistosoma eggs are eliminated with feces or urine, depending on species.
• Under appropriate conditions the eggs hatch and release miracidia, which swim and penetrate specific snail intermediate hosts.
• The stages in the snail include two generations of sporocysts and the production of cercariae.
• Upon release from the snail, the infective cercariae swim, penetrate the skin of the human host, and shed their forked tails, becoming schistosomulae.
• The schistosomulae migrate via venous circulation to lungs, then to the heart, and then develop in the liver, exiting the liver via the portal vein system when mature.
• Male and female adult worms copulate and reside in the mesenteric venules, the location of which varies by species (with some exceptions).

Species-Specific Locations

• S. japonicum is more frequently found in the superior mesenteric veins draining the small intestine.
• S. mansoni occurs more often in the inferior mesenteric veins draining the large intestine.
• However, both species can occupy either location and are capable of moving between sites.
• S. intercalatum and S. guineensis also inhabit the inferior mesenteric plexus but lower in the bowel than S. mansoni.
• S. haematobium most often inhabits in the vesicular and pelvic venous plexus of the bladder, but it can also be found in the rectal venules.
• The females (size ranges from 7–28 mm, depending on species) deposit eggs in the small venules of the portal and perivesical systems.
• The eggs are moved progressively toward the lumen of the intestine (S. mansoni, S. japonicum, S. mekongi, S. intercalatum/guineensis) and of the bladder and ureters (S. haematobium), and are eliminated with feces or urine, respectively.

Signs and Symptoms

Above all, schistosomiasis is a chronic disease.

Schistosoma haematobium (Urinary Tract)

• Painless blood stained urine at the end of urination (haematuria)
• Frequency of urination (cystitis and fibrosis)
• Hydronephrosis, pyonephrosis, hypertension, uraemia.
• Fatigue
• Genital sores

Schistosoma mansoni (GIT)

• Abdominal pain
• Frequent stool with blood stained mucous
• Palpable liver (hepatomegaly)
• Haematemesis
• Cough
• Diarrhea
• Fever
• Fatigue

Other Symptoms

• Skin symptoms: At the start of infection, mild itching and a papular dermatitis of the feet and other parts after swimming in polluted streams containing cercariae.

Diagnosis

• History of staying in an endemic area.
• Urine examination (for Schistosoma haematobium ova)
• Stool examination (for Schistosoma mansoni ova)
• Bladder x-ray for calcification or Ultrasound for urinary tract
• Cystoscopy.
• Detection of parasitic antigens by ELISA (blood sample).
• Tissue biopsy: (rectal biopsy (snip) for all species and biopsy of the bladder for S. haematobium) may demonstrate eggs when stool or urine examinations are negative.

Treatment

Schistosomiasis is readily treated using a single oral dose of the drug Praziquantel annually, (40mg/kg).

Prevention

• Avoid defecating or urinating in or near water
• Avoid washing or stepping in contaminated water
• Effective treatment of cases
• When a village reports more than 50 percent of children have blood in their urine, everyone in the village receives treatment.
• Clear bushes around landing sites
• Eliminating the water-dwelling snails that are the natural reservoir of the disease. Copper sulfate and Niclosamide can be used for this purpose.