Malaria is one of the world's most important tropical diseases, causing great human suffering and loss of life in the affected countries. There are four species of Plasmodia causing human malaria: P. falciparum, P. vivax, P. ovale, and P. malariae. Of the four species of Plasmodia, it is P. falciparum with which causes the most problems. Mosquito control is often not cost-effective in areas where the disease is most severe and where transmission interruption cannot be sustained. Therefore, current malaria control places emphasis on early diagnosis, treatment with effective antimalarials, and selective use of preventive measures including vector control where they can be sustained. The treatment of malaria has changed over the past two decades in response to declining drug sensitivity in P. falciparum and a resurgence of the disease in tropical areas. Some other problems are increasing numbers of severe and cerebral malaria cases, the high cost of drugs, side effects and the need for multiple dose regimens. Although chloroquine was recently the drug of choice in Africa, resistance has now spread to all major malarial-endemic areas. For multidrug resistant P. falciparum malaria, the choice of treatment is mefloquine, halofantrine, or quinine plus tetracycline. After mefloquine became the drug of choice in some Southeast Asian countries, P. falciparum malaria resistant to mefloquine developed. The alternative treatment with oral quinine or quinidine is not well tolerated. Although the combination of quinine with tetracycline or doxycycline remains more than 85 percent effective nearly everywhere (Watt et al., 1992), compliance with seven-day courses of treatment required for resistant P. falciparum infections is poor. The second-line drug, a combination of a long-acting sulfonamide (usually sulfa-doxine) and pyrimethamine carries a risk of severe side effects and is facing growing resistance.
Traditional remedies derived from plants continue to be a source of interesting biologically active compounds. A highly promising new class of antimalarial drug is derived from qinghaosu - a substance extracted from a plant which the Chinese have used to control fever for at least two thousand years. Artemisinin and its derivatives have been proven to be potent antimalarials - this chapter will concentrate on the clinical aspects of the treatment of falciparum malaria with these agents.
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