1. Malaria Plasmodium life cycle PRAKASH JHA M.Sc. BIOINFORMATICS
Roll No. 25
Plasmodium life cycle

2. Introduction:
Malaria is a disease caused by protozoa & it is widespread in tropics, subtropics and certain areas of temperate zones.
Malaria means bad air.
Causative agent of malaria is Plasmodium.
Plasmodium belongs to class Sporozoa of Phylum Protozoa.
Out of 60, only 4 species of plasmodium cause malaria in men.
Plasmodium vivax
Plasmodium ovale
Plasmodium malariae
Plasmodium falciparum

3. History:
Plasmodium, the causative agent of malaria, discovered by Charles Laveran.
Lancisi suspected relationship b/w mosquito & malaria.
Roland Ross(1897) discovered relationship b/w mosquito & malaria & got Nobel Prize in 1902.

4. Plasmodium- a digenetic parasite
Plasmodium is protozoan parasite and spends its life in two hosts (Digenetic).
The two hosts are:
Man : Primary/definitive host (Adult parasite live & causes fever)
Anopheles Mosquito(female) : Intermediate host.
Anopheles carries the malarial parasite from infected human host to a fresh human host whom it bites, hence mosquito is also a vector.

5. Life cycle: in human(Asexual)
Infected mosquito bites an individual
Saliva rich in Sporozoites (infected stage) injected
Sporozoites enter the circulation and then the liver
Sporozoites multiplies in liver cell & forms merozoites
Merozoites enter RBC forming trophozoites which mature to become Schizonts
Merozoites discharged into blood stream when red cell degenerate
This results in attack of malarial fever
Red cell destroyed by spleen
Some merozoites continue to develop in liver.

6. In Mosquito : sexual
Some merozoites develop into male/female gametocytes.
During mosquito bite , these gametocyte are ingested
Gametocyte fertilize in mosquito intestine.
Sporozoites enter human blood on mosquito bite.
Sporozoites localizes in salivary glands of mosquito.
Development of Sporozoites
Completion of cycle.

7. Plasmodium life cycle

8. Phases of life cycle in human
Pre- Erythrocytic Phase
Sporozoites enter the liver and multiplies
Erythrocytic Phase
Merozoites enter RBC & forms trophozoites.
Exo- Erythrocytic Phase
Some Merozoites continue to develop in liver.
This Phase absent in falciparum malaria.

9. Importance of mosquito as a vector
Gametocytes (mega/micro) remain in blood for several weeks but are unable to develop further in human host because of the high body temperature of man. It is therefore necessary for them to be taken into the body of anopheles(female) as mosquito is cold blooded animal.

10. Fever cycle:
In early stage, fever may persistent for several days but soon it develops into synchronous periodicity.
A classical attack of fever has chill, rise in temp. to °C headache & Myalgia.
This is followed by several hour of profuse sweating & fall in temperature.
These paroxysms occur every in:
48 hours(In vivax & ovale malaria)
72 hours(In quartan malaria)
In falciparum malaria, the temperature is usually persistently elevated or may progress to 48 hour cycle.

11. Features of plasmodium species
Malaria Types
Incubation Period
Striking Features
Plasmodium ovale
Mild tertian malaria
14 days
Schizonts & gametocytes enlarge the infected erythrocytes
Plasmodium vivax
Benign tertian malaria
Plasmodium malariae
Quartan malaria
30 days
Erythrocytes are not enlarged
Plasmodium falciparum
Cerebral malaria
(fatal)
12 days
Ring shaped trophozoites, Gametocytes are crescent shaped

12. Symptoms: High fever headache Liver is moderately enlarged Nausea
Vomiting
Diarrhea
Rarely jaundice may occur
anemia

13. Laboratory diagnosis:
Thick & thin blood films are taken .The typical morphology of parasite within the erythrocyte allows differentiation of plasmodium species.
It can also be demonstrated on bone marrow examination & by splenic puncture.

14. Treatment: Chloroquine for vivax, ovale & malariae
Primaquine is important to destroy the liver hypnozoite stages of vivax & ovale.
Quinine, mefloquine for falciparum
Chloroquine
Recently, Tu Youyou win nobel prize for her work in helping to create an anti­malaria medicine ( Artemsinin).

15. prevention:
Anopheles mosquitoes usually feed during the night so you can protect yourself by  sleeping under a bed net.
Indoor residual spraying of the walls and other surfaces can kill them reducing the chances that infected mosquitoes spread the disease from one household to another
The number of mosquitoes may be controlled by eliminating  mosquito larvae before they reach adulthood.
Wear cloths that covers full body.

16. Sickle cell anemia (a gift of nature)
In SCA there is replacement of Glu ß6 of HBA with Val in Hbs.
Heterozygous for SCA lead a normal life even through their erythrocytes have shorter lifetime than normal individuals.
The gene responsible for tendency of RBCs to sickle also alters the permeability of plasma membrane of sickle cell, causing potassium ions to leak out. Low levels of potassium kill malarial parasite.

17. Sca : example of balancing selection
The sickle cell mainly occur in Africa where malaria is major cause of death.
The women who are heterozygote have higher fertility; that’s why natural selection has not eliminated the allele.
The loss of deleterious recessive genes through deaths of homozygotes is being balanced by the gain resulting from successful reproduction by heterozygotes . For this reason, the selection is called as balancing selection.

18. From where malaria came to humans?

19. Origin of malaria in humans:
Gorilla was the original source of human infection by P. falciparum.
Researchers revealed a genetic match b/w human P. falciparum organisms & those infecting wild gorillas.
Using single genome amplification technique they identified DNA sequence from parasite found in fecal samples from wild gorillas
This proved that parasite jumped species from gorillas to human.

20. References:
aspx
Allison , A.C., The discovery of resistance to malaria of sickle-cell heterozygotes, Biochem. Mol. Biol. Educ. 30, 279–287 (2002)
Human malaria parasites may have originally come from gorillas ­ Health News ­ NHS Choices
A Fresh Look at the Origin of Plasmodium falciparum , the Most Malignant Malaria Agent.

21. ANY QUESTIONS ?

22. Thank You