Most common parasitic disease. 200 million cases each year
of which over a million die.
Found throughout the tropics except Polynesia and Micronesia.
Risk increased by:
- Haemoglobin S, C, E
- No Duffy blood group antigens Fya or Fyb (West Africa)
- α- and β-Thalassaemia
- G6PD deficiency
Protozoan parasite. Four sorts:
- Plasmodium falciparum, (East Africa, South America)
- P. vivax, (Central America, South America, North Africa, South Asia)
- P. ovale, (West Africa)
- P. malariae
The vector is female anopheline mosquitoes.
Sporozoites—initial Anopheles mosquito innoculum.
They invade the liver to form schizonts.
Schizonts: replication within hepatocytes/erythrocytes to form merozoites.
Merozoites: invade erythrocytes to form trophozoites. They cannot
re-invade the liver.
Trophozoites: form in erythrocytes. They multiply to form schizonts.
Gametocytes: form from merozoites, which can be taken up by the mosquito.
In falciparum malaria, parasitised erythrocytes express PfEMP-1 which binds ICAM-1 on
Pathological effects are dependent entirely on asexual replication in
Non-falciparum malaria is rarely fatal.
Death is most commonly due to cerebral malaria or severe anaemia.
Hypnozoites form only in P. vivax and P. ovale.
P. falciparum trophozoites adhere to venular endothelium, reducing
blood flow and causing stagnant anoxaemia.
Unrousable coma, convulsions.
Dyserythropoiesis (which contributes to the anaemia), iron sequestration,
Acute transient GN,
quartan malarial nephrosis.
ARF due to hypovolaemia:
adherence of parasites in renal vasculature and haemoglobinuria
Pulmonary oedema, secondary bronchopneumonia,
Enlarged spleen stuffed with malarial pigment, phagocytosed cells.
Splenic rupture is more common in P. vivax infection.
Quinine causes release of insulin by β islet cells.
Glucose requirements also increased by fever, anaerobic glycolysis,
metabolic demands of malarial parasites.
- Admit to ICU.
- Nurse in bed because of postural hypotension.
- Quinine IV.
- Control pyrexia with paracetamol, tepid sponging.
- Record vital signs, GCS regularly.
- Control convulsions with diazepam.
- Transfusion when PCV falls below 20%
- Careful fluid balance (↑vol: pulmonary oedema, ↓vol: shock, renal failure, lactic ↓pH)
- Pulmonary oedema treated with oxygenation, mechanical ventilation, haemoperfusion.
- Hypoglycaemia from quinine.
- Exchange transfusion for hyperparasitaemia.
- Splenic rupture: rapid surgical intervention
Non falciparum malaria
- Well covered
- Mosquito net
- Wearing mosquito repellant
- Synthetic pyrethroids improve prophylaxis
- Chloroquine resistant P. falciparum absent: chloroquine only.
- Chloroquine resistant P. falciparum not widespread: chloroquine + proguanil.
- Chloroquine resistant P. falciparum widespread: mefloquine.
- Mefloquine resistant P. falciparum: doxycycline.
Current research centres around vaccines based on circumsporozoite protein.
A candidate vaccine should offer 100% protection in