Life Cycle
Plasmodium completes its life cycle inside the bodies of both male and female Anopheles mosquitoes. As a result, life follows a digenetic pattern. The major or definitive host is man, and the secondary or intermediate host or vector is the female anopheles mosquito.
To complete its life cycle, Plasmodium falciparum, the major pathogenic organism, requires both the Anopheles mosquito and humans. In the mosquito, the protozoan’s sexual cycle takes place. When a mosquito bites the skin to feed on man’s blood, the insect’s saliva contains immature sporozoites, which are passed to humans.
It is divided into 3 phases
(a) Pre-erythrocytic schizogony,
(b) Exo-erythrocytic schizogony,
(c) Erythrocytic schizogony.
The infective stage is the sporozoite. An infected mosquito injects sporozoites into a man’s body while sucking blood. To continue pre- and exoerythrocytic schizogony, the sporozoites reach the liver.
The parasites enter the human body through the liver, reproduce, and then enter the bloodstream, where they attack red blood cells for their hemoglobin. The merozoites are released when red blood cells burst, allowing them to assault new red blood cells. When an RBC ruptures, a poison called haemozoin is released. This results in a high fever and a cold. A high number of merozoites are formed during these cycles. Every 48 hours, the erythrocytic cycle repeats, coinciding with the onset of malaria symptoms. The erythrocytic cycle produces certain merozoites that never assault fresh RBC. They are patiently waiting for the mosquito to be sucked. Some merozoites mature into sexually mature gametocytes, which are then passed on to another biting mosquito. The sexual cycle of the mosquito begins with gametocytes. Male and female gametocytes are the two types available. Inside the mosquito’s gut, they reproduce sexually.
In the body of a mosquito, the sexual phase of the life cycle takes place at a low temperature. The male or microgametocyte produces 4-8 microgametes after entering the mosquito’s stomach. Exflagellation is how this happens. Only one macrogamete is produced by the female or macrogametocyte. A zygote is formed when a microgamete and a macrogamete unite. The zygote produces an elongated ookinete that enters the mosquito’s gut wall. After that, the ookinete transforms into a spherical oocyst. To create sporoblasts, the oocyst splits. A huge number of sporozoites are produced by each sporoblast. This is referred to as sporogony. The sporozoites are injected along with the saliva when an infected mosquito bites a healthy male. The release of merozoites from red blood cells causes the fever cycles to occur every two or three days (Plasmodium falciparum) or three days (Plasmodium vivax).
Malaria affects mammals other than humans, including bats, rats, and primates, as well as birds and reptiles. Female Anopheles mosquitos are the only ones that feed on blood and hence transmit malaria. Males are unable to pass the sickness on to their female partners.