Schistosomiasis is caused by three major trematodes, which includes Schistsoma Mansoni, Schistsoma Japonicum and, and Schistsoma Haematobium. The previous two species inhabit venules of the intestines where as the latter are found mostly in the venules of the urinary tract. Human infection occurs as a result of penetration of the unbroken skin by the free-swimming cercariae. This often occurs in individuals who have frequent contact with water bodies heavely infested with appropriate snails.

Diagnosis is by identification of the ova in the feces in cases of S. mansoni and S. japonicum and urine in case of S. haematobium or tissues in all cases.

Treatment

First line:

Praziquantel, 40 mg/kg in 2 divided doses 4-6 hours apart on one day or 1200 mg p.o. as a single dose or 2 divided doses for both S. haematobium and S. mansoni

S/E: minor Gastero-intestinal upset.

C/I: ocular cysticercoids.

Dosage forms: tablet, 600 mg.

Alternatives:

Metrifonate, 600 mg p.o. tid at 14 days interval for S. haematobium.

S/E: nausea, colic, lassitude

C/I: recent exposure to insecticides

D/I: Respiratory paralysis when given with depolarizing neuromuscular blockers

Dosage forms: tablet, 100mg.

Oxamniquine, 1250 mg (30 mg/kg) p.o. once for S. mansoni.

S/E: headache, dizziness, drowsiness and minor GI disturbances.

C/I: should not be used in pregnancy.

Dosage forms: capsule, 250 mg; suspension, 250-mg/5ml