Quinine giving a further half dose. No injectable preparation of quinine is licensed in the US; quinidine is used instead. Quinine is a flavor component of tonic water and bitter lemon drink mixers. On the soda gun behind many bars, tonic water is designated by the letter "Q" representing quinine. According to tradition, the bitter taste of anti-malarial quinine tonic led British colonials in India to mix it with gin, thus creating the iconic gin and tonic cocktail, which is still popular today. Nowadays, the amount of quinine in tonic is much lower and drinking it against malaria is useless. Quinine
Human genetic resistance to malaria foothold among African populations until larger sedentary communities emerged in association with the evolution of domestic agriculture in Africa (the agricultural revolution). Several inherited variants in red blood cells have become common in parts of the world where malaria is frequent as a result of selection exerted by this parasite. This selection was historically important as the first documented example of disease as an agent of natural selection in humans. It was also the first example of genetically controlled innate immunity that operates early in the course of infections, preceding adaptive immunity which exerts effects after several days. In malaria,