Word: malariae
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...development of chloroquine. More effective than quinine, it was hailed as a wonder drug. Wartime research also yielded a wonder pesticide: DDT. It was the potent combination of chloroquine and massive DDT spraying in Asia, South America and Africa (and even in the U.S., where there were pockets of malaria as recently as 1950) that fostered WHO's rosy vision of conquering malaria once...
...nature fought back, however. War in Southeast Asia and political instability in countries like Idi Amin's Uganda interfered with eradication efforts. Premature reports of success against malaria led some health authorities to relax their vigilance. Then came the worst blows of all: in the mid-1960s, Plasmodium falciparum, the most lethal of the four species of parasite that cause human malaria, showed signs of becoming resistant to chloroquine. Soon there were resistant strains on three continents. About the same time, health officials around the Mediterranean began to find mosquitoes that were immune to DDT. It was a classic...
...Malaria research had largely come to a halt during the years that chloroquine and DDT seemed all conquering. But Dr. Ruth Nussenzweig of N.Y.U. continued to pursue a malaria vaccine, a goal many viewed as impossible. The malaria bug presented unique obstacles. The first was the complex life cycle of the Plasmodium parasite, which is in a sense three bugs in one (see diagram): the sporozoite, which enters the human bloodstream when an infected mosquito bites; the merozoite, which invades the red blood cells and causes the disease's chills and fever; and the gametocyte, which, when ingested...
...vaccines work by teaching the immune system to recognize the face of the enemy. Once the body knows the chemical features, or antigens, of an infectious agent, it can produce specific weapons, or antibodies, against it. With malaria, however, there are three faces to recognize. Each stage is marked by different antigens, and antibodies against one stage will not provide protection against another. Nussenzweig and her immunologist husband Victor decided to focus their efforts on a sporozoite vaccine. In 1967 she showed that it was possible to protect mice against malaria by injecting them with sporozoites that had been rendered...
...fast enough to catch sporozoites after they have been injected into the body by a mosquito: each sporozoite takes only a few minutes to find sanctuary in the liver, where it is safe from the marauding antibodies. Even if only a handful of sporozoites get through to the liver, malaria will result...