Plasmodium vivax life cycle

Over 100 Plasmodium species contribute to the spread of malaria, but only four of these (P. falciparum, P. vivax, P. ovale, and P. malariae) account for human infection, the deadliest being P. falciparum. The malaria life cycle exists first in a mosquito, and then it passes to a human host. An infected female Anopholes mosquito is the host of the parasite s sporogonic hfe cycle. Mature P. falciparum sporozoites reach the salivary glands of the mosquito, and the parasite is transmitted to a human host when the mosquito feeds. During this blood meal, sporozoites are released into the bloodstream where they penetrate hepatic cells and mature into schizonts. The liver cells rupture after approximately two weeks, discharging merozoites into the bloodstream whereupon they infect red blood cells (RBCs). Every 48 to 78 hours, mature merozoites rupture from... 

Alphonse Laveran, a French Army physician working in North Africa in the 1880s, was the first to observe malarial parasites in human blood. Their mode of transmission was not understood, however, until Ronald Ross, a British medical officer in India, found the organisms within the bodies of Anopheles mosquitoes. Malaria is caused by four species of parasitic protozoa Plasmodium vivax, P. ovale, P. malariae, satid P. falciparum. These organisms have complex life cycles involving several different developmental stages in both human and mos-... 

Malaria is a devastating human disease that causes more than 850 000 deaths each year. The disease is caused by a protozoan parasite of the genus Plasmodium, which is obligate intracellular protozoan parasites of humans and animals, and the symptoms of the disease are largely a consequence of the asexual multiplication of these parasites within erythrocytes in the host. The Human disease is caused by the Plasmodium species P. falciparum, P. vivax, P. ovale and P. malariae. The life cycle of the Malaria parasite is extremely complex involving distinct cellular morphologies for infection of the host organism (human or other animal) and the infectious vector, the mosquito... 

A remarkable genetic study of the function of all of the members of the Plasmodium kinome has recently been completed by Tewari, Billker and coworkers.15 Whilst such a study, if carried out in a human Plasmodium species (e.g. P. falciparum or P. vivax) would be limited by being applicable to the erythrocytic phase of the life cycle, Tewari and co-workers used the rodent species, P. berghei, which permitted an analysis of the effects of each kinase knock-out in both asexual and sexual stages of the life cycle. As noted... 

Malaria parasites have a complex life cycle that permits drug action at several points. Plasmodium species that infect humans P falciparum, P malariae, P ovale, P vivax) tire spread by the female Anopheles mosquito and, after inoculation into the human host, undergo a primary developmental stage in the liver (primary tissue phase). They then enter the blood and parasitize erythrocytes (erythrocytic phase). P falciparum and P malariae have only one cycle of liver cell invasion thereafter, multiplication is confined to erythrocytes. The other species have a dormant hepatic stage (in which they become bypnozoites) that is responsible for recurrent infections and relapses after apparent recovery of the host from the initial infection. 

Figure 6.1. The life cycle of the malaria parasites, Plasmodium malariae, P. ovale, and P. vivax (solid and dashed lines). and P. falciparum (solid line)...

The mutation however confers an important advantage on its carriers if they reside in a malaria-afflicted area of the world. Plasmodium vivax (one protozoon responsible for malaria) requires entry to the erythrocytes of its host during its life cycle. Sickle cells because of their fragility are rapidly degraded by the spleen. Any parasite contained within these cells will also be destroyed by splenic activity. 

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