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Microbiology · Apicomplexans

Plasmodium malariae and Plasmodium ovale !

  • Parasite
  • Exam priority: medium

Two less common malaria species: P. malariae gives fever every 72 hours and can harm the kidney; P. ovale forms hypnozoites like vivax.

Updated 2026-11-01

Also called: quartan malaria (P. malariae), ovale tertian malaria

At a glance

Shape
P. malariae: band forms and rosette schizont; P. ovale: oval, fimbriated red cell
Family
Plasmodiidae
Type
Intracellular apicomplexan protozoa (liver and red blood cells)
Stain
Giemsa on thick and thin films
Size
P. malariae does not enlarge the cell; P. ovale enlarges it slightly

Morphology

  • P. malariae: normal or small red cell, band or basket trophozoites and coarse dark pigment.
  • P. malariae: schizont with few merozoites arranged in a rosette.
  • P. ovale: slightly enlarged, oval red cell with fimbriated edges; may show Schüffner's dots.
  • P. ovale: compact trophozoite with coarser pigment than vivax.

Transmission

  • Bite of an infected female Anopheles.
  • P. malariae can pass through transfusion years after infection because of its low, persistent parasitemia.

Reservoir: Humans

Vector: Female Anopheles mosquitoes.

Isolation precautions

What the care team adds to standard precautions.

  • Standard

Life cycle

  1. The mosquito injects sporozoites that reach the liver.
  2. In the liver they form schizonts; P. ovale also leaves dormant hypnozoites, P. malariae does not.
  3. Merozoites invade red cells: P. malariae prefers old cells, P. ovale young ones.
  4. The blood cycle lasts about 72 hours in P. malariae and about 48 hours in P. ovale.
  5. Gametocytes form and are taken up by mosquitoes, where the sexual phase produces sporozoites.

Virulence factors

  • P. malariae: low parasitemia that can persist for decades without symptoms.
  • P. malariae: immune-complex deposits in the glomerulus, with nephrotic syndrome in chronic infection.
  • P. ovale: hypnozoites that cause relapses.

Diseases it causes

  • Malaria from P. malariae (quartan) or P. ovale (tertian with relapses). Malaria →
  • Nephrotic syndrome from chronic or repeated P. malariae infection.

Clinical picture

  • P. malariae: fever every third day (every 72 hours), usually mild.
  • P. ovale: illness similar to vivax, with relapses.
  • Chronic P. malariae: edema and proteinuria from nephrotic syndrome, especially in children.

Diagnosis

  • Giemsa thick and thin films; species are told apart on the thin film.
  • Band forms and rosette schizonts suggest P. malariae; oval, fimbriated cells suggest P. ovale.
  • PCR to confirm species, since they are confused with P. vivax or mixed infections.

Treatment

Chloroquine or another blood schizonticide; for P. ovale an 8-aminoquinoline (primaquine or tafenoquine) is added against hypnozoites after G6PD testing. P. malariae needs no anti-relapse treatment.

Drug class only; doses and regimens are set by the clinician from the current guideline.

Prevention

  • The same anti-Anopheles measures: insecticide-treated nets, repellents and screens.
  • Blood-donor screening according to each country's rules.
  • Species diagnosis in travelers returning from Africa, where P. ovale is more common.

Vaccine: There is no vaccine against these species.

Test yourself

Think of the answer, then tap the question to see it.

Which Plasmodium species causes nephrotic syndrome?

P. malariae, through immune-complex deposits in the glomerulus during chronic or repeated infection.

Which of these two species forms hypnozoites?

P. ovale; like P. vivax, it needs an 8-aminoquinoline to prevent relapse.

Which fever pattern goes with P. malariae?

Quartan fever: a paroxysm every 72 hours.

Which thin-film forms are typical of P. malariae?

Band trophozoites stretching across the cell and schizonts with merozoites in a rosette, in red cells that are not enlarged.

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Educational content on microorganisms; not a treatment guide and no substitute for a health professional's advice. No doses are given.

Sources: CDC - DPDx - Malaria (CDC, 2024); Clinical Features of Malaria | Malaria | CDC (CDC, 2024); Malaria (WHO, 2025).

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