sentences:  The correlation between infectious disease and average IQ was confirmed, and they concluded that the "evidence suggests that infectious disease is a primary cause of the global variation in human intelligence".Malaria affects 300–500 million persons each year, mostly children under age five in Africa, causing widespread anemia during a period of rapid brain development and also direct brain damage from cerebral malaria to which children are more vulnerable.A 2006 systematic review found that Plasmodium falciparum infection causes cognitive deficits in both the short- and long-term.