Abstract

Schistosomiasis is becoming more prevalent, especially in tropical Africa, where new irrigation systems are being built in which fresh water snails, the intermediate host of the disease, can thrive. In most areas measures to control the snails have proved unsatisfactory and expensive. Treatment of infected individuals has also been unsatisfactory: the antimonial preparations, niridazole (Ambilhar) and hycanthone (Etrenol)^1,2 may be effective but are certainly toxic. Infection (mainly of the intestine) with Schistosoma mansoni and S.japonicum may also lead to hepatic fibrosis with porto-systemic shunting. This further complicates therapy as niridazole, the most widely used drug, cannot be used because the unmetabolised compound reaches the brain and causes a confusional state or psychosis.³