Molecules Versus Malaria

The parasite malaria that once infected human beings around the globe, now only affects certain regions, mostly Africa, thanks to a handful of molecules that have either fought malaria itself, or have attacked it at its source: the mosquito.  The four species of malaria that infect humans are Plasmodium vivax, P. falciparum, P. malariae, and P. ovale.  These four species of malaria would square up with three molecules that would ultimately eliminate this parasite from most of the world.  The first of these molecules is quinine, an alkaloid found in the bark of Cinchona (genus) trees.  First prescribed by native Americans to visiting Europeans to combat fever, Chinchona bark was soon used as a remedy for malaria in Europe.  Quinine, also known as Jesuit's powder (it was Jesuit missionaries who introduced the bark to Europe), proved to be very effective in fighting malaria, and one of its derivatives, chloroquine, was an even greater success, and soon replaced its parent molecule.  The second molecule, DDT, which was explained in the previous chapter, was used as an insecticide against the anopheles mosquito, which spread malaria from person to person by sucking their blood.  Used extensively and liberally, DDT had completely eliminated malaria in Europe by 1975, and in many other regions of the world, except in Africa.  However, Africans do have their own natural defense against malaria:

Hemoglobin, found in red blood cells, transports oxygen around the body.  In 25% of Africans however, sickle cell anemia is present and most with this disease die before adulthood.  About 50% of Africans are carriers of the disease, but surprisingly, being a carrier is the best case scenario.  Though they are not fully affected by the anemia, the anemic hemoglobin works to their advantage as it provides immunity from malaria.  Those who have normal hemoglobin are subject to malaria so it is mostly carriers of sickle cell anemia who are able to pass on their genes to the next generation.  However, due to carriers being heterozygous, the ratio of anemics to carriers to normal hemoglobin should remain relatively the same, unless of course something is done to upset this balance.  Until then however, anemic hemoglobin serves as a protection against malaria along with quinine and formally DDT, the three of which have saved millions of lives.