* Malaria: Malaria is caused by a parasite called Plasmodium. There are several species of Plasmodium that can infect humans, but the most common are *Plasmodium falciparum*, *Plasmodium vivax*, *Plasmodium ovale*, and *Plasmodium malariae*.

* Dengue: Dengue is caused by a virus called dengue virus. It belongs to the family *Flaviviridae* and is transmitted by mosquitoes. There are four distinct serotypes of dengue virus, all of which can cause illness.

Important Note: While both malaria and dengue are spread by mosquitoes, they are caused by different types of organisms: a parasite in the case of malaria and a virus in the case of dengue.