Pages Below:

Malaria

Organisms

    • Plasmodium falciparum
    • Plasmodium vivax
    • Plasmodium ovale
    • Plasmodium malariae

Transmission

  • Spread by bite of infected mosquitos

Course

  • Non-specific prodromal symptoms
  • Paroxysms
    • Fatigue
    • Aches
    • Nausea
    • Dizziness
    • Trickling sensation
    • Mild fever
  • Acute febrile illness
    • Rigors
    • Sweating
    • Periodic – 48-72 hours depending on species
    • Severity and course depends on species & strain of parasite
  • Relapse and recrudescence
  • Relapse in P.vivax, P. ovale.
    • Reactivation of hepatic hypnozoites
    • Ill patient
      • Anaemia
      • Jaundice
      • Hepatosplenomegaly
      • Multiple organ dysfunction
  • Recrudenscesc in P. falciparum, P.malariae
    • Exacerbation of persistent undetectable parasitaemia
    • No exo-erythrocytic cycle
  • Incubation period
    • Inversely proportional to dose of sporozoites
    • Increased by immunity, chemo prophylaxis
    • 65-95% western travellers develop malaria within 1 month

Natural Immunity

  • West Africans who lack Duffy antigen cannot develop Plasmodium vivax malaria as there are none of the receptors to which the merozoites attach

  • Haemoglobin S, glucose-6-phosphate dehydrogenase deficiency, thalasseamia, pyruvate kinase deficiency all offer resistance to Plasmodium falciparum.

    • retards P. falciparum maturation

    • reduces severity of disease

P. falciparum malaria

most important species

    • Responsible for nearly all deaths (2 million annually)
    • Complications
      • Cerebral malaria
      • ARDS
      • Renal failure
      • Hpatic dysfunction
      • Hypoglycaemia (5%)
        • Also occurs with quinine
      • Fluid & electrolyte & acid-base disturbances
      • Circulatory collapse
      • Algid malaria
      • Massive haemolysis

Non-falciparum malaria

generally milder

    • Lower parasitaemia
    • Relapse or recrudescence
    • P. malariae associated with nephritic syndrome

In pregnancy

  • transplacental infection leads to maternal or fetal death

Diagnosis

  • Blood films – thin/thick

Treatment

  • Quinine
  • Mefloquine
  • Artemisin derivatives
  • Malarone
  • Chloroquine – non-falciparum malarias
  • Primaquine – liver stages
  • doxycycline
  • sulphadoxine + pyrimethamine (Fansidar)
  • atovaquone + proguanil

Prevention of infection important

  • Covering bare skin
  • Mosquito nets
  • Reducing standing water