malaria is a disease that originates in a parasitic protozoan (plasmodium) that lives within a mosquito. when an infected mosquito bites an animal or human, the parasite is transmitted into the blood. the disease then takes on a complex form that can severely affect the immune system. because malaria is transmitted through mosquitoes, it is restricted to specific environmental conditions. of all the people infected with malaria, children comprise 90%. the following map illustrates the global distribution of malaria risk.