parasitic protists of human importance : disease : malaria agent : plasmodium 4 species differential...
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Parasitic protists of human
importance :
Disease : Malaria Agent : Plasmodium 4 species
Differential pathogenicity
Vector-borne Apicomplexan inhabiting liver & blood
Global malaria mortality between 1980 and 2010:
a systematic analysis
Murray et. al. 2012Lancet vol 379, February 4
2012
Key findings: Mortality burden higher in adults than previously estimated. Significant decline in mortality in Africa.
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.
Malaria
Plasmodium falciparum : Most pathogenic species. Entirely confined to tropics and subtropics. Clinically sharply differentiated from the other three species. Malignant tertian.
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
Plasmodium vivax
Plasmodium ovale
Plasmodium malariae
Complications• Cerebral malaria
• Anemia
• Renal disease
• Blackwater fever
• Dysenteric malaria
• Algid malaria
• Hyper-reactive malarial splenomegaly (HMS)
Malaria and pregnancy
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
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
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
Prevention and Control
• Malaria control strategy• Early diagnosis &
treatment
• Selective & sustainable prevention against parasite & vector
• To detect & contain epidemics
• To reassess regularly a country’s malaria situation
• Roll back malaria campaign/WHO strategy –Note : impregnated bednets
First results of Phase 3 Trial of RTS,S/AS01
malaria vaccine in African children
The RTS,S Clinical Trials Partnership
New England Journal of Medicine, November 17, 2011
vol 365, no. 20
Current leading recombinant pre-erythrocytic malaria vaccine candidate: RTS,S/AS01or AS02 (circumsporozoite protein)