Abstract
At present, praziquantel is the only antischistosomal drug available for the treatment of schistosomiasis, a parasitic disease that affects over 200 million people in the tropics and subtropics. However, a number of medicinal plants, such as artemether, artesunate (artemisinins), cyclosporin and mirazid have shown promising results in recent years. Artemisinins, which are obtained from the Chinese herb Artemisia annua, have been shown to be effective, safe and easily administered. Artemether administered at doses of 25-400 mg/kg has resulted in worm reduction rates of up to 99% in laboratory animals. The incidence of Schistosoma mansoni was reduced by 50% in children treated with artemether at a dose of 6 mg/kg in Africa. Artesunate administered at doses of 30-300 mg/kg induces worm reduction rates of as high as 99%, 7 days postinfection. In humans, up to 100% protection against Schistosoma japonicum has been obtained by administering artesunate at a dose of 6 mg/kg at 1- or 2-week intervals for 13 doses. In addition to their prophylactic effects, recommended doses for the treatment of malaria of artemisinins are effective against schistosomiasis. Cyclosporin A (CsA), which is an immunosuppressive drug, is also highly effective against schistosomiasis. CsA, obtained from a fungus (Tolypocladium inflatum), confers a high degree of protection (90-100%) against infections or re-infection by S. mansoni in mice. Mirazid is an extract of myrrh, an oleo gum obtained from the stem of a plant called Commiphora molmol. It is widely used in the treatment of schistosomiasis in private clinics in Egypt. However, there are contradictory reports on the efficacy of this drug, ranging from 8.9 to 91.7%.