Plasmodium malariae

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Plasmodium malariae
Giemsa-stained micrograph of a mature Plasmodium malariae schizont
Scientific classification
Kingdom: Protista Phylum: Apicomplexa Class: Aconoidasida Order: Haemosporida Family: Plasmodiidae Genus: Plasmodium Species: P. malariae
Binomial name
Plasmodium malariae Feletti & Grassi, 1889

Plasmodium malariae is a parasitic protozoa that causes malaria in both humans and dogs. It is closely related to Plasmodium falciparum and Plasmodium vivax which are responsible for most malarial infection. It is a so-called "benign malaria" and is not nearly as dangerous as that produced by P. falciparum or P. vivax. P. malariae causes fevers that recur at approximately three-day intervals (a quartan fever), longer than the two-day intervals of the other malarial parasites.

Microscopically, the parasitised red blood cell (erythrocyte) is never enlarged and may even appear smaller than that of normal red blood cells. The cytoplasm is not decolorized and no dots are visible on the cell surface. The food vacuole is small and the parasite is compact. Cells seldom host more than one parasite. Band forms, where the parasite forms a thick band across the width of the infected cell, are characteristic of this species (and some would say is diagnostic). Large grains of malarial pigment are often seen in these parasites: more so than any other Plasmodium species. 8 merozoites

P. vivax and P. ovale that has been sitting in EDTA for more than half-an-hour before the blood film is made will look very similar in appearance to P. malariae, which is an important reason to warn the laboratory immediately when the blood sample is drawn so they can process the sample as soon as it arrives.