All

Plasmodium ovale is a species of parasitic protozoa that causes tertian malaria in humans. It is one of several species of Plasmodium parasites that infect humans including Plasmodium falciparum and Plasmodium vivax which are responsible for most malarial infection. It is rare compared to these two parasites, and substantially less dangerous than P. falciparum.

P. ovale has recently been shown by genetic methods to consist of two subspecies, P. ovale curtisi and P. ovale wallikeri.

The larvae are found in clear seepage water, in roadside pools, in rice fields, and in other similar habitats. Pools that are sunlit, at least part of the day, seem to be preferred, although larvae are occasionally found in rather densely shaded pools. Heavy production of larvae often occurs in matted algal growths in water along the margins of rice fields. The females enter houses readily and feed on man. They are more active at dusk and during the night but occasionally do attack man during the daylight hours in dense shade or on cloudy days. (Carpenter and LaCasse 1955)