Li Shizhen (1518–1593)
The most promising drug now used for the treatment of malaria dates back to 168 BCE in ancient China, when the weed qing hao (sweet wormwood, annual wormwood) was recommended for the treatment of hemorrhoids. Some five centuries later, in 340, the herb was an ingredient in a tea intended to reduce fevers. In 1596, the Chinese herbalist Li Shizhen recommended this tea for the relief of the chills and fever of malaria in his Compendium of Materia Medica.
In the late 1960s, Chinese scientists began a search for active drugs found in plants that had long been used in their traditional remedies. In 1972, they isolated qinghaosu—better known by its international name, artemisinin—from the leaves of Artemesia. Tests showed that the artemisinins, a collective term that includes derivatives of the natural chemical, very effectively clear the body of the malaria-causing Plasmodium parasites—in particular, Plasmodium faciparum, the most common and deadly strain.
The history of most antimalarial drugs teaches us that, as their use increases, so do drug-resistant strains of parasites. One of the greatest fears among the experts who treat malaria is the development of artemisinin resistance by currently susceptible plasmodia—fears confirmed in 2009 with reports of early signs of resistance. To forestall this possibility, the World Health Organization has urged that this drug only be used in combination with other antimalarial drugs.
In 2009, the United States joined more than eighty other countries worldwide and approved the use of Coartem, the first approved fixed-dose artemisinin combination therapy (ACT) for the treatment of malaria. A three-day treatment yields cure rates of more than 95 percent, even in areas where the parasite is resistant to multiple drugs.
Malaria, the most common parasitic infectious disease affecting humankind, kills more than 1 million people each year. Although malaria is not a problem in North America and western Europe, there are an increasing number of cases contracted by tourists and businesspersons when they visit the roughly ninety malaria-endemic countries.
SEE ALSO Quinine (1820), Chloroquine (1947).
This malaria-causing protozoan parasite is transmitted by a bite of the female Anopheles mosquito. The head of a mosquito is shown here magnified 100x.