Malaria(Plasmodium falciparum)- Epidemiology, Life Cycle, Prevention and Eradication
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Malaria(Plasmodium falciparum)- Epidemiology,
Life Cycle, Prevention and
Eradication
Sarath
Epidemiological TriadHost1.Sex-Male2.Race-Sickle cell trait3.Occupation-Labourers,Farmers,Tribals4.Socio Economic status 5.Human Habits -Nomadism
Environment1.Seasons2.Temperature3.Humidity4.Rainfall5.Altitude
Agent Factors1.Parasites2.Reservoirs3.Relapses
VectorAnopheles Mosquito
Organism
Plasmodium Falciparum
Phylum : Apicomplexa
Class : Sporozoea
Subclass : Coccidia
Order : Eucoccidia
Suborder : Haemosporina
Features of plasmodium falciparum
Forms in the peripheral blood- Rings and crescents only.
Ring form- Cytoplasm fine and regular. Often with 2 nuclei. Form accole.
Merozoites- 18 to 24 or more. Arranged in a grape like cluster.
Gametocyte- Banana shaped. Larger than the red blood cell.
Life CycleExogenous Phase(in Mosquito)Sexual Cycle (sporogony)
Endogenous Phase(in Human)Asexual Cycle(Schizogony)
Sporozoites pass through body cavity,salivary glands
Exoerythrocytic cycle multiplication in liver parenchymal cells
Merozoites
Enter RBC
Ring Trophozoite
Mature Trophozoite
Immature Schizont
Mature Schizont
Microgametocyte(differentiation)Macrogametocyte
Human blood enters mosquito
Microgamete(fertilization)Macrogamete
Zygote
Ookinete(motile Zygote)
Penetrates to outer layer of stomach wall of mosquito and encysts
Oocyst grows(multiple division stage: cyst bursts to release sporozoites
Sporozoites in saliva injected into human host
Malaria Life Cycle in Humans
ReservoirConditions :
1. The person must harbour both sexes of gametocyte in blood
2. Gametocytes must be mature
3. Gametocytes must be viable
4. Gametocytes must be present in suffcientquantity
Reservoir Contd…
Humans
1. One who harbours the sexual forms of parasite.
2. Children are more likely to be gametocyte carriers than adults. Hence better reservoir.
Transmission
1. Vector Transmission
Anopheles culicifacies – Rural and per urban areasAnapheles stephensi -- Urban and Industrial areasAnopheles fluviatilis -- Hilly areasAnopheles epiroticus -- Only in Andaman and Nicobar
2. Direct Transmission
By sharing syringes, blood transfusion etc.
Parasites keep their infective activity during at least 14 days in bottles stored at -4 0C
Persons who have lived in endemic area and anyone who has had malaria should not be accepted as a blood donor until 3 years afterwards.
3. Congenital Malaria
Congenital infection from mother to newborn also occur, but it is comparatively rare
Prevention
All that we have to do is to break this chain
Insecticide treated nets
Repellents protective clothing screening of houses
Environmental sanitation
water management
drainage
Larviciding of water surfaces
intermittent irrigation slucing, biological control
Indoor residual spraying
Space spraying
Ultra low volume sprays
Health education
Community participation
Prophylaxis for susceptible population
Gametocidaldrugs
Prevention
Action For Individual and Family protection
Reduction of Human-Mosquito contact Insecticide treated nets, repellents, protective clothing, screening of houses
Destruction of mosquito larva Peri-Domestic sanitation
Source reduction Small scale drainage
Social participation Motivation for personal and family protection
Destruction of Adult Mosquitoes Indoor residual spraying
Prevention
Action For Community protection
Reduction of Human-Mosquito contact Insecticide treated nets, zooprophylaxis
Destruction of mosquito larva Larviciding of water surfaces, intermittent irrigation, sluicing, biological control
Source reduction Environmental sanitation, water management, drainage
Destruction of Adult Mosquitoes Indoor residual spraying, Space spraying, ultra low volume sprays
Social participation Health Education, Community participation
Biological Control-Gambusia
Insecticide treated nets
Can malaria be Eradicated???
AgentSource
SusceptiblePopulation
Vector
Eradication Elimination Control
Current answer is NO Why??
Despite progress, the burden of malaria is still great and it is widespread.
Drug and insecticide resistance are on the rise. In South East Asian countries, resistance of Plasmodium falciparum, to Artemisinin, has been detected.
Although new drugs and insecticides are being sought, none are expected to be available in the near future.
Ref: Malaria eradication:Is it possible?Is it worth it?Should we do it?Should we do it?Jenny Liu,Sepideh Modrek,Roly D Gosling,Richard GA Feachem
Increased mobility of people not only makes containment of resistance difficult, but also threatens the introduction or reintroduction of malaria parasites to receptive areas.
New strains are emerging- ex. Plasmodium knowlesi
Zoonotic reservoirs
Ref: Malaria eradication:Is it possible?Is it worth it?Should we do it?Should we do it?Jenny Liu,Sepideh Modrek,Roly D Gosling,Richard GA Feachem
How can we bring eradication in the future???
Malaria is biologically and ecologically different throughout the world. So Malaria eradication strategies should be developed and implemented on a local or regional level.
Eradication can be accelerated by new drug regimens and strategies that lead to complete parasitologiccure of the individual.
The majority of malaria infections occur in asymptomatic people, who are a source of continued transmission. A successful and accelerated eradication effort will target asymptomatic infections through community-based efforts.
Thank You
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