Plasmodium is a genus, belonging to the parasitic group ofprotozoa. At present, more than 200 species of this genus areidentified, out of which about 10 species infect humans. Amongseveral species, Plasmodium falciparum is reported to causemaximum health complications and mortality in humans. Acuteplasmodium infections, if left untreated, can progress to life-threatening conditions, whereas chronic infections can lead tosevere anemia. It also infects animals like rodents, monkeys aswell as birds. Plasmodium requires two hosts to complete its lifecycle, namely, a mosquito vector and a vertebrate host. Extensivestudies have been conducted on P. falciparum, as this protozoacauses malaria. Lets discuss in brief about the life cycle of P.falciparum.
The Vertebrate Stage: Initial InfectionThere are two distinct phases within thevertebrate stage; the hepatic phase and theblood phase. When a mosquito carrying thedisease bites a host, sporozoites enter into thebloodstream.The Hepatic PhaseSporozoites infect liver cells and mature intocapsules called schizonts. These eventuallyrupture to release merozoites, which continue tomultiply in the liver.
The Blood PhaseMerozoites eventually infect red blood cells wherethey become trophozoites. These will then matureinto schizonts that will rupture, releasing moremerozoites. This process will continue repeatedly.Some trophozoites mature into gametocytes that willeventually be ingested by a mosquito.
The Mosquito Stage: InfectionWithin the mosquito, male and female gametocytescombined to form zygotes. These mature into mobileookinetes that move to the mosquitos midgut and developinto a oocysts. The oocysts than grow andrupture, releasing sporozoites.The Mosquito Stage: TransmissionThe sporozoites travel to the mosquitos salivaryglands, where they will wait until the mosquito bites ahost. The sporozoites are transmitted to the host throughthe mosquitos saliva, restarting the life cycle.