Life cycle of Plasmodium
Plasmodium species complete their life cycle in two hosts;
1. In human; Asexual reproduction take place in human host in liver cell as well as red blood cells.
2. In mosquito; sexual reproduction takes place in mosquito.
1. Human cycle
Sporozoite is infective form of malarial parasite.
These sporozoites are present in salivary gland of female Anopheles mosquitoes.
Man gets infection by bite of Infected mosquito and enter blood circulation.
Through blood parasite, they enter in liver cell humans where they multiply asexually called schizogony.
Thus human cycle starts following stages;
1. Pre- erythrocytic schizogony
Under developing phase inside liver cells.
2. Erythrocytic schizogony
Penetrates red blood cell.
3. Gametogony
Develop in red blood cells, these are sexual forms.
4. Exo- erythrocytic schizogony
Produce merozoites (motile stage of parasite life cycle, release from host red blood cell for destroyed or invade cells.
Merozoites attack red blood cells.
2. Mosquito cycle
Sexual cycle of malaria parasite actually starts in human host by formation of gametocytes which are then transferred to mosquitos for further development.
The gametocytes convert into gametes in mosquito stomach.
Flagellated male gametes (sperm) fuse with female gamete (ova) and produce zygote.
Zygotes form oocysts.
By asexual multiplication of oocysts, many sporozoites are formed which then enter mosquito salivary glands.
From these, they are injected by mosquitoes bite into another human victim to begin cycle again.
1. Sporozoite enter in man
2. Sporozoite enter in human blood /and enter in liver.
3. In liver (exo erythrocytic cycle) sporozoites convert into merozoites.
4. In blood (erythrocytic cycle) merozoites convert into trophozoites.
5. Trophozoites multiply in RBCs and producing new merozoites.
6. Release of merozoites when RBCs repture and can infect other red blood cells.
7. In blood some merozoites become gametocytes.
a. Macrogametocyte female
b. Microgametocyte male
8. Female mosquito pickup gametocytes from human by sucking blood (sexual cycle of parasite mosquito).
9. In mosquito Macrogametocyte changes into Macrogamete (ova) and microgametocyte changes into microgamete (sperm).
10. Fertilization occurs by fusion ova and sperm, zygote formation occurs.
11. Cyst formed around the zygote called oocyst.
12. Oocyst contain sporozoites.
13. Sporozoites enter salivary gland of mosquito.
14. Bite of mosquitoes infective mosquito Saliva.
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