Presentation can be vague, any or all of wide variety of symptoms.
Always should be considered in unwell patients returning from or having passed though endemic areas


Parasite is a plasmodium (protozoan). 4 species infect humans:

  • P.falciparum (80% cases worldwide, highest mortality)
  • P.vivax
  • P.ovale
  • P.malariae



By the bite of the female anopheline mosquito
(can also be aquired transplacentaly, by transfusion or inoculation.)

Life Cycle of parasite


  • Very important tropical disease – occurs throughout tropics and subtropics at altitudes below 1500m
  • 0.5-2 million deaths per year (mostly <5yrs)

Protective factors

Red blood cells genetic factors

  • Sickle cell trait (HbS) is relatively protected against P. falciparum malaria (àbiologic advantage)
  • Duffy blood group negative red blood cells are resistant to infection by P. vivax.

Acquired immunity can develop after repeated attacks. A person can still be infected by malaria parasites but may not develop severe disease. (this is usually lost In pregnancy).


  • Haemolysis of RBCs and adherence of infected RBCs to capillaries and cytokine release.
  • In falciparum, RBCs containing schizonts adhere to capillary epithelium in the brain, kidney, liver lungs and gut vessels become congested
  • Organs anoxic.
  • Rupture of schizonts liberate toxic and antigenic substances that may cause further damage


Thick and thin blood films. Look for trophozoites and % RBC infected. High % (>30%) has high mortality


Quinine in mainstay of treatment (IV if >2% RBC infected)
Resistance of p.falciparum to chloroquine in widespread)
Supportive measures in severe disease.


  • Mosquito nets and well covering clothing
  • Insect repellant and indoor spraying (ie DDT)
  • Prophylaxis medications
    •  Doxycycline (cheapest, taken daily for 2 weeks prior to visiting and 4 weeks after returning from endemic area, SE include sunlight hypersensitivity, nausea and diarrhea).
    • Malarone (most expensive, taken daily for 2 days before and 7 days after trip, fewer side effects)
    • Larium (combination medication, taken weekly for 2 weeks prior to visiting and 4 weeks after returning from endemic area contraindicated in those with history of epilepsy or psychiatric disorders due to neuropsychiatric side-effects such as anxiety and hallucinations)


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