malaria

• swamps are breeding grounds for

  mosquitoes
• malaria is caused by

  protozoan parasite, Plasmodium (5-6 species infect humans)
• 175 species of Plasmodium
• 91 countries at risk of malaria
• ~90% of all malaria deaths occur in African region
• Plasmodium that infect humans

  • falciparum
  • vivax
  • malariae
  • ovale
  • knowlesi
• zoonotic malaria parasite transmitted to man from non-human primate hosts
• life cycle of Plasmodium 


  developmental (sporogonic) in mosquito, exo-erythrocytic (outside RBCs), erythrocytic cycle (in RBCs)
• no intermediate host for malaria
• direct human to human via mosquito
• falciparum is dangerous-responsible for majority of deaths
• vivax is acute, self-limiting, no complications or death
• acute febrile illness 


  shows signs of fever
• fever is periodic due to synchronised erythrocyte destruction
• tertian is every 


  3 days
• quartan is every 


  4 days
• malaria is transmitted by bite of female Anopheles mosquito
• Introduced malaria


  Local mosquito infected by biting people who have malaria
• Airport malaria


  Transported by aircraft from malaria endemic country to non-endemic country
• Transfusion malaria


  Via blood transfusion
• Mainline malaria


  Via shared needles and syringes
• Congenital malaria


  Infected mother transmit to child during pregnancy
• exo-erythrocytic cycle is in the liver
• sporozoites enter human when mosquito takes blood meal
• sporozoites are in the saliva
• sporozoite must penetrate hepatocytes in 30 minutes to circulate bloodstream and initiate infection
• when in liver, Plasmodium undergoes

  schizogony (asexual reproduction), divides nucleus to form merozoites (30,000-40,000)
• ruptured schizont release merozoites which can infect RBCs
• some Plasmodium can form hypnozoites
• hypnozoites are less sensitive to antimalarial drugs (can then reactive years later)
• merozoite invades RBCs
• merozoite multiplies by asexual reproduction
• merozoite is the disease causing stage
• gametocytes infect female mosquito
• trophozoite comes from merozoite
• trophozoites ingest haemoglobin to give haemozoin which accumulates in food vacuole
• Plasmodium modifies RBC membrane to enable it to take up nutrients
• schizont develop from trophozoite
• trophozoite divides to give 8-16 merozoites and are released when RBCs rupture
• mosquito stage

  • gametocyte
  • ookinete
  • oocyst
  • sporozoite