Malaria survives on healthy red blood cells and carriers don't have many healthy red blood cells. In the same way that people with hemochromatosis starve bubonic plague, carriers of sickle cell anemia starve malaria of red blood cells. The proactive effect of malaria only works on those who have a copy of sickle cell anemia and not on the actual disease. If you have sickle cell anemia, you are more likely to get malaria. However, malaria is such a violent disease that anything that can help in the fight against it and towards survival and reproduction is useful. Sharon Moalem and Jonathan Prince's book, Survival of the Sickest, highlights the fact that diseases don't always need to be cured, in fact beneficial mutations are how we evolve. While the book primarily discusses how diseases evolve humans, Moalem and Prince discuss how we humans shape diseases. With the simple act of procuring and giving away mosquito nets, you force the malaria virus to find a new path that is perhaps less harmful to its survival and reproduction, a path that may not cure the malaria virus but may not make it fatal, similar to the common