The significance of Medical Parasitology

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Parasitic protists of human importance
Disease Malaria Agent Plasmodium 4
species Differential pathogenicity Vector-borne
Apicomplexan inhabiting liver blood
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Global malaria mortality between 1980 and 2010a
systematic analysis

• Murray et. al. 2012
• Lancet vol 379, February 4 2012

Key findings Mortality burden higher in adults
than previously estimated. Significant decline in
mortality in Africa.
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Malaria

• Plasmodium vivax Most predominant and only
  species which extends to temperate regions.
  Benign tertian. Relapses.
• Plasmodium ovale Tropical Africa, occasionally
  S. America and Asia. Ovale tertian. Relapses
• Plasmodium malariae Primarily subtropical. Less
  frequent. Quartan.

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Malaria

• Plasmodium falciparum Most pathogenic species.
  Entirely confined to tropics and subtropics.
  Clinically sharply differentiated from the other
  three species. Malignant tertian.

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Malaria diagnosis

• Microscopy Blood smears thin versus thick
  smears
• Differentiation from P. falciparum (medical
  emergency in non-immune)
• Rapid diagnostic antigen test
• Serology
• Gene amplification methods

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Plasmodium vivax
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Plasmodium ovale
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Plasmodium malariae
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Complications

• Cerebral malaria
• Anemia
• Renal disease
• Blackwater fever
• Dysenteric malaria
• Algid malaria
• Hyper-reactive malarial splenomegaly (HMS)

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Malaria and pregnancy
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Pathogenesis

• Sequestration cytoadherence stage
  strain-specific parasite-derived ligands
• Host secreted proteins cytokines TNF and
  interleukins
• Differential ability to infect RBCs
• RBC recognition and invasion
• Paroxysm

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Epidemiology

• Transmission characteristics of the vector
• Other forms of transmission (blood transfusion,
  shared needles, congenital)
• Innate resistance red blood cell defects
• Immunity
• Control eradication versus containment

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Treatment malaria

• Management of severe falciparum malaria
• Chloroquine-resistant P. falciparum
• Chloroquine-sensitive P. falciparum or P. vivax,
  P. ovale and P. malariae
• Severe falciparum chemotherapy
• Chemotherapy for P. vivax and P. ovale
• Chemotherapy for P. malariae

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Prevention and Control

• Malaria control strategy
• Early diagnosis treatment
• Selective sustainable prevention against
  parasite vector
• To detect contain epidemics
• To reassess regularly a countrys malaria
  situation
• Roll back malaria campaign/WHO strategy

• Note impregnated bednets

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First results of Phase 3 Trial of RTS,S/AS01
malaria vaccine in African children
Current leading recombinant pre-erythrocytic
malaria vaccine candidate RTS,S/AS01or AS02
(circumsporozoite protein)

• The RTS,S Clinical Trials Partnership
• New England Journal of Medicine, November 17,
  2011 vol 365, no. 20