Antimalarial drug research. A wormwood plant, Artemisia annua, sealed in a glass growth chamber. This plant is exposed to radioactively labelled carbon dioxide gas for purposes of investigating artemisinin extraction processes. Artemisinin is a substance which has been used to treat fever in Chinese herbal medicine for over 2000 years. Artemisinin derivatives have been extracted from Artemisia annua and are being tested as potent antimalarial drugs. Malaria is a disease caused by the presence of protozoan parasites within the red blood cells. It is transmitted by mosquito bites and symptoms include chills, fever, anaemia and other complications which may be fatal.