Plasmodium, life cycle

Antimalarial dragp interfere with, or are active against, die life cycle of die plasmodium, primarily when it is present in the red blood cells. Destruction at this stage of die plasmodium life cycle prevents die development of die male and female forms of the plasmodium. This in turn keeps die mosquito (when die mosquito bites an infected individual) from ingesting the male and female forms of the plasmodium, thus effectively ending die plasmodium life cycle (Pig. 16-1). 

Detection by LDMS and structural elucidation of other secondary metabolite products, generated in the host during the onset of the parasite disease, is discussed. These molecules may serve as additional biomarkers for rapid malaria diagnosis by LDMS. For instance, choline phosphate (CP) is identified as the source of several low-mass ions observed in parasite-infected blood samples in addition to heme biomarker ions. The CP levels track the sample parasitemia levels. This biomarker can provide additional specificity and sensitivity when compared to malaria detection based on heme ion signals alone. Furthermore the observed elevated CP levels are discussed in the context of Plasmodium metabolism during its intra-erythrocytic life cycle. These data can... 

To date, no effective vaccine has been developed for many parasites, notably the malaria-causing parasitic protozoa Plasmodium. One of the major difficulties in such instances is that parasites go through a complex life cycle, often spanning at least two different hosts. 

The malaria parasite Plasmodium has a complex life cycle with several forms and spends much of its life hiding within red blood cells.1 It may also suppress the immune system. The unicellular sporozoites, which are injected into the bloodstream by mosquitos, are protected by an external coat protein that is unusual in containing many short repeated sequences. For example, that of P. falciparum, which causes the most deadly form of malaria, contains the sequence Asn-Ala-Asn-Pro repeated 37 times.q These coat proteins undergo unusually rapid evolution, which makes the preparation of vaccines difficult.1... 

The life cycle of Plasmodium requires two vectors for completion. The definitive hosts are female mosquitoes from the genus Anopheles. Anophelesgambiae and Anopheles funestus are two such definitive hosts in the African Region, while Anopheles darlingi transmits malaria in South and Central America (6-8). The second host is a vertebrate that may be a bird, reptile, or small mammal. The malaria species listed above are all able to utilize humans as a vertebrate host. 

The effectiveness of a drug treatment is related to the particular species of infecting plasmodium and the stage of its life cycle. A summary of the life cycle of the parasite and the sites of therapeutic interventions are presented in Figure 35.4. 

Anti-malarial activity of desferrioxamine has been demonstrated in a range of Plasmodium species under in vitro conditions and more importantly under in vivo conditions in rat [87] and man [88], Desferrioxamine causes reversible effects during early ring stage and late schizont stages of the life cycle. In contrast, irreversible cytocidal effects occur when cultures at the late trophozoite/early schizont stage are exposed to the chelator [89,90]. Primary lesions are associated with the nucleus which is consistent with a perinuclear localization for ribonucleotide reductase [88]. 

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-... 

Protozoal infections. Malaria is the major transmissible parasitic disease in the world. The life cycle of the plasmodium that is relevant to prophylaxis and therapy is described. Drug resistance is an increasing problem and differs with geographical location, and species of plasmodium. 

Survival of parasites is partly due to their high rate of reproduction, which may be either sexual or asexual some organisms such as Plasmodium exhibit both forms of reproduction in their life cycle. Simple fission is characteristic of many amoeba, but some species also undergo nuclear division in the cystic state (cysts are forms required for survival outside the host) with each nucleus giving rise to new trophozoites (the growing, motile and pathogenic form). 

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