Medicinal plants and the control of protozoal disease, with particular reference to malaria.

Malaria and other protozoal diseases continue to pose serious health problems world-wide. Resistance of the malaria parasites, Plasmodium spp., to drugs such as chloroquine (and, more lately, quinine) occurs with increasing frequency and underlies the necessity to develop new agents for malaria chemotherapy; in the case of diseases caused by species of Leishmania and Trypanosoma there has always been a marked paucity of effective drugs, particularly those with a wide safety margin and minimal or no undesirable side effects. Novel drugs, are required to help alleviate morbidity and mortality and to contribute to the world-wide control of these diseases, in part by helping to reduce the reservoirs of infection. Reliance upon plants for the treatment of disease is high in the developing world and such plants offer a source of new molecules. Research centered upon Plasmodium has produced a number of findings which now prompt the formulation of important questions which may influence and focus the direction of phytotherapy research in the future.