Malaria is a serious, sometimes fatal, disease spread by mosquitoes and caused by a parasite. It’s typically transmitted through the bite of an infected Anopheles mosquito. Infected mosquitoes carry the Plasmodium parasite. When this mosquito bites a human, the parasite is released into the body. Once the parasites are inside the body, they travel to the liver, where they mature. After several days, the mature parasites enter the bloodstream and begin to infect red blood cells. Within 48 to 72 hours, the parasites inside the red blood cells multiply, causing the infected cells to burst open. Malaria is typically found in tropical and subtropical climates where the parasites can live. The World Health Organization (WHO) estimates that about 3.2 billion people are at risk of malaria.