Malaria is the single leading cause of death, especially among children, in the developing world. Malaria is caused by infection with parasites of the genus Plasmodium, transmitted by mosquitos. In addition to transmission, vital steps in the parasite lifecycle occur in the mosquito host. The invention offered for licensing relates to therapeutic compounds and related pharmaceutical compositions that can be used in the prevention and treatment of malaria infection. More specifically, the invention is drawn to compounds that may kill sexual and mosquito stage malaria parasites to block transmission. Specifically claimed is the antihistamine Ketotifen, which has demonstrated activity blocking parasite development in mosquitoes. Also claimed are treatments encompassing Ketotifen with other existing antimalarial drugs in a combination treatment aimed at multiple stages in the malaria life cycle.