Plasmodium ovale

Plasmodium ovale

Plasmodium ovale in a blood smear

Plasmodium ovale is a protozoan parasite and one of the species of Plasmodium that cause malaria in humans. It is one of the five species of Plasmodium that commonly infect humans, the others being Plasmodium falciparum, Plasmodium vivax, Plasmodium malariae, and Plasmodium knowlesi.

Morphology

Microphotograph of Plasmodium ovale microgametocyte in Giemsa-stained thin blood film, showing Schüffner's dots and hemozoin pigment

Plasmodium ovale is characterized by its oval-shaped infected red blood cells, which are slightly larger than uninfected cells and have a fimbriated edge. The presence of Schüffner's dots and hemozoin pigment is also a distinguishing feature. The parasite undergoes a complex life cycle involving both asexual and sexual stages.

Life Cycle

The life cycle of Plasmodium ovale involves two hosts: the human host and the Anopheles mosquito. In humans, the parasite undergoes asexual reproduction in the liver and red blood cells. The sexual stage occurs in the mosquito, where the parasite undergoes fertilization and development into sporozoites, which are then transmitted back to humans through a mosquito bite.

Epidemiology

Relative incidence of Plasmodium species by country of origin for imported cases to non-endemic countries

Plasmodium ovale is primarily found in sub-Saharan Africa, but it can also be found in parts of Asia and the Western Pacific. It is less common than Plasmodium falciparum and Plasmodium vivax. The incidence of Plasmodium ovale is often underestimated due to its similarity to Plasmodium vivax and the lack of specific diagnostic tools.

Clinical Features

Infection with Plasmodium ovale causes a form of malaria that is generally less severe than that caused by Plasmodium falciparum. Symptoms include fever, chills, headache, and muscle aches. The disease can cause relapses due to dormant liver stages known as hypnozoites.

Diagnosis and Treatment

Microphotographs of Plasmodium ovale in Giemsa-stained thin blood films

Diagnosis of Plasmodium ovale infection is typically made by microscopic examination of blood smears stained with Giemsa. Molecular methods such as PCR can also be used for more accurate diagnosis. Treatment involves the use of antimalarial drugs such as chloroquine and primaquine, the latter being used to eliminate hypnozoites and prevent relapses.

Related Pages

• Malaria
• Plasmodium falciparum
• Plasmodium vivax
• Anopheles