Asexual Life Cycle of Plasmodium Falciparum

plasmodium spp possess a life cycle which shows an alternation of generation accompanied by an alternation of host. Man represent the intermediate host of malarial parasite, i.e. Asexual life cycle (cycle of schizogony) occurs in Man. The gametogony also starts in the RBC of man and is completed in the Female Anopheles mosquito.

Pre-erythrocytic schizogony

1. It comprises a single cycle and lasts for six days
2. The mature pre-erythrocytic schizont measures 60 micro meter in length and 30 micro meter in breadth
   
   
   
3. It contains numerous small merozoites about forty thousands in number
4. Merozoites enter in to RBC to start erythrocytic schizogony. These merozoites are liberated on the 7^th day of infection and enter in to RBC to start erythrocytic schizogony. It is now known that they do not re-enter into the liver cells and pre-erythrocytic schizogony disappear completely without giving rise to late tissue phase.

Erythrocytic Schizogony

1. Plasmodium falciparum does not show special affinity for any particular type of RBC but invades both the reticulocytes and erythrocytes (i.e. both young and mature RBC).
2. Schizogony occurs inside the capillaries of the internal organs (spleen, liver and Bone marrow) hence only the ring form (but not the growing trophozoites and schizonts) are found in the peripheral blood.
3. The cycle of Schizogony is completed in about 36 to 48 hours.
4. Multiple infection of the RBC i.e. more than one plasmodium falciparum parasite invades a single RBC (Generally 2-6 parasite).

Gametogony

Plasmodium falciparum has characteristics gametocytes of diagnostic significance. It has sickle-shaped or banana shaped (i.e. Crescent) gametocytes. Gametogony occurs inside the capillaries of bone marrow and spleen. With the growth of gametocyte, the red blood cell is gradually used up and only its skin remains in the form of a sheath enclosing the parasite. The size of the mature gametocyte is about one and a half times larger than the red blood cell harbouring it.

Exo-erythrocytic Schizogony
Exo-erythrocytic schizogony is completely absent in Plasmodium falciparum. So in falciparum malaria relapses does not occur.