Malaria is a disease caused by parasites of the genus Plasmodium, which are single-celled eukaryotic organisms classified as protozoa. These parasites are transmitted to people through the bites of infected female Anopheles mosquitoes. Cholera is caused by bacteria (Vibrio cholerae). Diphtheria is caused by bacteria (Corynebacterium diphtheriae). Pneumonia can be caused by various pathogens including bacteria, viruses, and fungi, but Malaria is definitively caused by a protozoan.