DurgicalDurgical
EN
Open the app

Microbiology · Apicomplexans

Plasmodium vivax !

  • Parasite
  • Exam priority: high

The most common malaria parasite in Colombia. Spread by Anopheles mosquitoes, it can sleep in the liver and cause relapses months later.

Updated 2026-11-01

Also called: vivax malaria, benign tertian malaria

At a glance

Shape
Ring, amoeboid trophozoite, schizont and round gametocyte
Family
Plasmodiidae
Type
Intracellular apicomplexan protozoan (liver and red blood cells)
Stain
Giemsa on thick and thin films: Schüffner's dots
Size
Enlarges the red cell 1.5 to 2 times

Morphology

  • Enlarged, pale infected red cells with Schüffner's dots (pink stippling).
  • Amoeboid, irregular trophozoite with fine yellow-brown pigment.
  • Mature schizonts with many merozoites; round to oval gametocytes.
  • All stages appear in peripheral blood, unlike P. falciparum.

Transmission

  • Bite of an infected female Anopheles, mostly at dusk and at night.
  • Rarely by transfusion, transplant, shared needles or from mother to fetus.
  • Not spread from person to person by contact.

Reservoir: Humans (a person with gametocytes in the blood)

Vector: Female Anopheles mosquitoes; in Colombia, species such as An. darlingi, An. albimanus and An. nuneztovari.

Isolation precautions

What the care team adds to standard precautions.

  • Standard

Life cycle

  1. The mosquito injects sporozoites into the skin while feeding.
  2. Sporozoites reach the liver, multiply as schizonts and release merozoites.
  3. Some parasites stay dormant in hepatocytes as hypnozoites, which can wake months or years later.
  4. Merozoites invade reticulocytes and go through ring, trophozoite and schizont; synchronized rupture causes fever.
  5. Some become male and female gametocytes.
  6. A mosquito takes up gametocytes; in its gut a zygote, oocyst and new sporozoites form and move to the salivary glands.

Virulence factors

  • Duffy-binding protein: enters red cells through the Duffy antigen; Duffy-negative people are at lower risk.
  • Preference for reticulocytes, which limits parasitemia.
  • Liver hypnozoites: relapses without a new bite.
  • Hemolysis and release of pigment and parasite products at each schizont rupture, which trigger cytokines and fever.

Diseases it causes

  • P. vivax malaria: usually uncomplicated, but it can be severe (anemia, thrombocytopenia, lung involvement, splenic rupture). Malaria →

Clinical picture

  • Paroxysms of chills, high fever and sweating; the blood cycle lasts about 48 hours (tertian fever).
  • Anemia, mild jaundice, splenomegaly and low platelets.
  • Relapses weeks to years later if hypnozoites are not cleared.
  • In pregnancy: maternal anemia and low birth weight.

Diagnosis

  • Giemsa-stained thick film: detects and counts parasites (the reference method in Colombia).
  • Thin film: identifies the species by morphology (enlarged cells, Schüffner's dots).
  • Rapid diagnostic tests (RDTs): useful where there is no microscopist; some detect only P. falciparum reliably.
  • PCR to confirm species or mixed infections at reference labs.
  • G6PD activity testing before primaquine or tafenoquine.

Treatment

A blood schizonticide (chloroquine, where the parasite is still susceptible) plus an 8-aminoquinoline to clear hypnozoites (primaquine or tafenoquine) after G6PD testing. Chloroquine-resistant P. vivax has been reported in some parts of the world.

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

Prevention

  • Insecticide-treated bed nets, indoor residual spraying and removal of breeding sites.
  • Repellents, covering clothes and window screens from dusk onward.
  • Prompt diagnosis and treatment of every case to break transmission.
  • Chemoprophylaxis for travelers on medical advice.

Vaccine: There is no vaccine against P. vivax. The RTS,S and R21 vaccines target P. falciparum and are not part of Colombia's PAI schedule.

Test yourself

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

Which P. vivax stage causes relapses?

The hypnozoite, a dormant liver-cell form that reactivates weeks or years later without a new bite.

Which test is ordered before giving primaquine?

G6PD enzyme activity, because primaquine can cause severe hemolysis in people with the deficiency.

Which thin-film finding points to P. vivax?

Enlarged, pale red cells with Schüffner's dots and amoeboid trophozoites.

Which red-cell antigen does P. vivax use to get in?

The Duffy antigen; Duffy-negative people are therefore at lower risk of infection.

What is the reference method for diagnosing malaria in Colombia?

The Giemsa-stained thick film, which detects and counts parasites; the thin film helps define the species.

Add to my cards (5)

← Back to the group: Apicomplexans

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); Malaria (WHO, 2025); Clinical Features of Malaria | Malaria | CDC (CDC, 2024); INS hace un llamado a reforzar acciones territoriales para combatir la malaria (Instituto Nacional de Salud (INS) Colombia, 2025).

Spotted a mistake?We are always improving for the community. Tell us what is wrong and our team will review it.Report a mistake

Representative model, for educational purposes only.