Herbs have been used over the centuries to fight disease. One such plant was the bark of the cinchona tree, which is native to South America. Back in the 1600s, Jesuit missionaries described how the bark could be dried, ground into powder, and then mixed with water to make a drink to treat people suffering from fevers. The missionaries probably learned about the treatment from native people, who'd been using it for a long time [source: Columbus].
This cure was not just a folk remedy. Cinchona bark became the source of a drug, quinine, which until the early 1900s was the only effective treatment for malaria. Quinine is an alkaloid that interferes with the growth and reproduction of the malarial parasites that take over a victim's red blood cells. The one catch is that quinine only kills those invaders, but not the ones who take over other cells in the victim's body. As a result, people who used quinine, often became sick again a few weeks later.
During World War II, better, manufactured treatments, such as chloroquine, were developed. However, as the malarial parasite that transmits the disease has become resistant to these synthetic drugs, quinine has been making a comeback — the parasite is still sensitive to it [source: Britannica.com].