Plasmodium Meaning: Plasmodium is a genus of obligate parasitic unicellular eukaryotes which live among vertebrates and insects. Plasmodium is a protozoan that has a life cycle that includes growth in a blood-feeding insect host before injecting parasites into a vertebrate host throughout a blood meal. Parasites develop in vertebrate body tissue (usually the liver) until infecting red blood cells in the bloodstream.
Malaria is a disease caused by the breakdown of the host's red blood cells. Few parasites are grabbed by a blood-feeding insect (mosquitoes in a number of situations) throughout this infection, extending the life cycle. Plasmodium belongs to the Apicomplexa phylum, a diverse group of parasitic eukaryotes. Plasmodium belongs to the Apicomplexa order Haemosporida and family Plasmodiidae. Plasmodium has been classified into 14 subgenera depending on parasite anatomy and host distribution. There are over 200 species of Plasmodium. Plasmodium species' evolutionary relationships would not necessarily meet taxonomic boundaries; several species which are morphologically similar or infect the very same host are found to be distantly related.
Plasmodium Protozoan Genus
Plasmodium species share certain characteristics with other eukaryotes, as well as those that are specific to their phylum or genus. In the nucleus, the Plasmodium genome is divided into 14 chromosomes. Plasmodium protozoa parasites keep a single copy of their genome for the majority of their lives, only doubling this for a short sexual exchange inside the insect host's midgut.
The endoplasmic reticulum (ER), which behaves similarly to the ER in other eukaryotes, is connected to the nucleus. Proteins are transported from the ER to the Golgi apparatus, which in Apicomplexans is usually a single membrane-bound compartment. Proteins are then transported to different cellular compartments or even to the cell surface from here. Plasmodium species contain multiple cellular structures at the apical end of the parasite that function as specialised organelles for secreting effectors into the host, similar to other apicomplexans. The bulbous rhoptries, that produce parasite proteins that are involved in entering the host cell and altering the host once within, are the most visible.
Micronemes, which have been smaller structures neighbouring to the rhoptries and include parasite proteins necessary for motility and also recognising and connecting to host cells, are located next to the rhoptries. Secretory vesicles named dense granules are found in the parasite and comprise parasite proteins that are involved in modifying the parasite-host membrane, known as the parasitophorous vacuole.
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Plasmodium has multiple stages in its life cycle in both insect and vertebrate hosts. In certain cases, parasites are transmitted into a vertebrate host through the bite of an insect host (typically a mosquito, with the exception of a few Plasmodium species of reptiles). Parasites attack the liver or even other tissues first, whereby these go through a single broad round of replication until leaving the host cell and infecting the erythrocytes. Some Plasmodium primates species may build a long-lived dormant stage termed as hypnozoite during this point.
It can last for over a year in the liver. Throughout most Plasmodium species, nevertheless, the parasites found in infected liver cells are just merozoites. They join red blood cells upon emerging out from the liver, as previously mentioned. They then go through continuous stages of erythrocyte infection, with a small percentage of parasites evolving into a sexual stage known as a gametocyte, which is picked up by an insect host that is eating blood. Invasion of erythrocytes by Plasmodium species in some hosts may result in malarial disease. This can be serious at times, leading to the host's death (e.g. P. falciparum in humans). Plasmodium infection appears to be asymptomatic in other hosts.
Plasmodium species can be found all over the world. To complete their life cycles, all Plasmodium species must move through a vertebrate host and an insect host. Plasmodium species have different host ranges, with some species limited to a single vertebrate and insect host, while others can infect multiple vertebrate and insect species.
Vertebrates: Plasmodium parasites have been found in a wide range of vertebrate hosts, such as reptiles, birds, and mammals. Although several species can infect multiple vertebrate hosts, they are usually restricted to one of these groups (such as birds). Humans are mainly infected by five Plasmodium bacteria, with Plasmodium falciparum causing the vast majority of serious disease and death. Some organisms that infect humans can also infect other primates, and zoonoses between primates (e.g., P. knowlesi) are common. Plasmodium species that do not normally infect humans can also be found in nonhuman primates. Some of these can cause serious illness in primates, while others can live in the host for long periods of time without causing illness.
Insects: Both Plasmodium species infect a bloodsucking insect host, usually a mosquito, in addition to a vertebrate host (although some reptile-infecting parasites are transmitted by sandflies). Plasmodium species are parasitized by mosquitoes of the genera Culex, Anopheles, Culiseta, Mansonia, and Aedes. Anopheles mosquitoes, which host Plasmodium parasites that cause human malaria, and Culex mosquitoes, which host Plasmodium species that cause malaria in birds, are the most well-studied of these. Since only female mosquitoes feed on the blood of vertebrate hosts, they are infected with Plasmodium. Different organisms have various effects on their insect hosts. Insects infected with Plasmodium may have a shorter lifespan and less ability to reproduce. In addition, it appears that certain Plasmodium species cause insects to tend to bite infected vertebrate hosts over non-infected hosts.
In 1880, Charles Louis Alphonse Laveran described parasites in the blood of malaria patients, which led to the discovery of Plasmodium. The parasite was given the name Oscillaria malariae by him. In 1885, zoologists Ettore Marchiafava and Angelo Celli reexamined the parasite and classified it as a member of the Plasmodium genus, named after the multinucleate cells of the same-named slime moulds. Camillo Golgi recognised in 1886 that many species could be involved in the development of various types of malaria.
Giovanni Batista Grassi and Raimondo Filetti identified the parasites that cause two forms of human malaria, Plasmodium vivax and Plasmodium malariae, shortly after Plasmodium falciparum was discovered and named by William Welch in 1897. Following that, the other two Plasmodium species that infect humans were identified: Plasmodium ovale (1922) and Plasmodium knowlesi (identified in long-tailed macaques in 1931; in humans in 1965). Ronald Ross described the function of insect hosts in the Plasmodium life cycle in 1897, and Giovanni Batista Grassi, Amico Bignami, and Giuseppe Bastianelli described it in 1899.
Cyril Garnham suggested dividing Plasmodium into nine subgenera based on parasite morphology and host specificity in 1966. This included four subgenera previously proposed by A. Corradetti in 1963 for Plasmodium species that infect birds. When Sam R. Telford reclassified Plasmodium parasites that infect reptiles in 1988, he added five subgenera to the scheme. G. Valkiunas reclassified the Plasmodium species that infect birds in 1997, adding a fifth subgenus: Bennettinia.