Republic of Congo (1963)
Quinine is derived from the bark of the plant Cinchona which is a native of Peru. Before its discovery, there was not effective treatment for malaria and most victims died. Quinine is a component of tonic (for gin and tonic) which was much favoured by the British colonists in the tropics. Their partiality for this drink was thought to account for their resistance to malaria and prolonged the British Empire. However, taken in overdose, quinine can cause retinal artery spasm and blindness.