Plasmodium+falciparum

__ Plasmodium falciparum ____ : ____ Malaria __

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 * __ Scientific Classification __**


 * ** Kingdom ** || Chromalveolata ||
 * ** Phylum ** || Apicomplexa ||
 * ** Class ** || Aconoidasida ||
 * ** Order ** || Haemosporida ||
 * ** Family ** || Plasmodiidae ||
 * ** Genus ** || Plasmodium ||
 * ** Species ** || falciparum ||

The **Apicomplexa** are a large group of protists, most of which possess a unique organelle called apicoplast and an //apical complex// structure involved in penetrating a host's cell. They are unicellular, spore-forming, and exclusively parasites of animals. Motile structures such as flagella or pseudopods are present only in certain gamete stages. This is a diverse group including organisms such as coccidia, gregarines, proclaims, haemogregarines, and plasmodia. Diseases caused by apicomplexan organisms include Babesiosis, Malaria, and Coccidian diseases. = **__ Introduction to species __** = The name malaria, from the Italian //mala aria//, meaning //bad air//, comes from the linkage suggested by Giovanni Maria Lancisi (1717) of malaria with the poisonous vapours of swamps. This species name comes from the Latin //falx// meaning //sickle//, and //parere// meaning //to give birth//. // Plasmodium falciparum // is the most deadly of the five //Plasmodium// species that cause human malaria. It is transmitted by the female //Anopheles// mosquito. Around the world, malaria is the most significant parasitic disease of humans and claims the lives of more children worldwide than any other infectious disease. Since 1900, the area of the world exposed to malaria has been halved, yet two billion more people are presently exposed. Morbidity, as well as mortality, is substantial. Infection rates in children in endemic areas are of the order of 50%: Chronic infection has been shown to reduce school scores by up to 15%. Reduction in the incidence of malaria coincides with increased economic output.
 * __ Description of Phylum: Apicomplexa __**



**__ Unique Morphological Features __**
Among medical professionals, the preferred method to diagnose malaria and determine which species of //Plasmodium// is causing the infection is by examination of a blood film under microscope in a laboratory. Each species has distinctive physical characteristics that are apparent under a microscope. In //P. falciparum//, only early (ring-form) trophozoites and gametocytes are seen in the peripheral blood. It is unusual to see mature trophozoites or schizonts in peripheral blood smears as these are usually sequestered in the tissues. The parasitised erythrocytes are not enlarged, and it is common to see cells with more than one parasite within them (multiply parasitised erythrocytes). On occasion, faint comma-shaped red dots called "Maurer's dots" are seen on the red cell surface. The comma-shaped dots can also appear as pear-shaped blotches.



(Blood smear from a //P. falciparum// culture (K1 strain - asexual forms). Several red blood cells have ring stages inside them. Close to the center, there is a schizont and on the left a trophozoite)


 * __ Unique Anatomical/Physiological Features __**

Like most Apicomplexa, malaria parasites harbor a plastid similar to plant chloroplasts, which they probably acquired by engulfing (or being invaded by) a eukaryotic alga, and retaining the algal plastid as a distinctive organelle encased within four membranes (see endosymbiotic theory). The apicomplexan plastid, or apicoplast, is an essential organelle, thought to be involved in the synthesis of lipids and several other compounds, and provides an attractive target for antimalarial drug development, particularly in light of the emergence of parasites resistant to chloroquine and other existing antimalarial agents.

**__ Adaptive Habitat Features __**

More recently, //P. falciparum// has evolved in response to human interventions. Most strains of malaria can be treated with chloroquine, but //P. falciparum// has developed resistance to this treatment. A combination of quinine and tetracycline has also been used, but there are strains of //P. falciparum// that have grown resistant to this treatment as well. Different strains of //P. falciparum// have grown resistant to different treatments. Often the resistance of the strain depends on where it was contracted. Many cases of malaria that come from parts of the Caribbean and west of the Panama Canal as well as the Middle East and Egypt can often be treated with chloroquine, since they have not yet developed resistance. Nearly all cases contracted in Africa, India, and southeast Asia have grown resistant to this medication and there have been cases in Thailand and Cambodia in which the strain has been resistant to nearly all treatments. Often the strain grows resistant to the treatment in areas where the use is not as tightly regulated.

Even though the disease can occur in almost any human on Earth who becomes infected, it is more prevalent in sub-Saharan Africa than in other regions of the world. In most African countries, more than 75% of cases were due to //P.falciparum//, whereas in most other countries with malaria transmission, other Plasmodial species predominate. A map based on the reported incidence of infection in 2007 is available at: [] ** Plasmodium life cycle ** The life cycle of all Plasmodium species is complex. Infection in humans begins with the bite of an infected female Anopheline mosquito. Sporozoites released from the salivary glands of the mosquito enter the bloodstream during feeding quickly invade liver cells (hepatocytes). Sporozoites are cleared from the circulation within 30 minutes. During the next 14 days in the case of //P. falciparum//, the liver-stage parasites differentiate and undergo asexual multiplication resulting in tens of thousands of merozoites which burst from the hepatoctye. Individual merozoites invade red blood cells (erythrocytes) and undergo an additional round of multiplication producing 12-16 merozoites within a schizont. The length of this erythrocytic stage of the parasite life cycle depends on the parasite species: 48 hours for //P. falciparum//, //P. vivax//, and //P. ovale// and 72 hours for //P. malariae//. The clinical manifestations of malaria, fever and chills, are associated with the synchronous rupture of the infected erythrocyte. The released merozoites go on to invade additional erythrocytes. Not all of the merozoites divide into schizonts, some differentiate into sexual forms, male and female gametocytes. These gametocytes are taken up by a female anophylean mosquito during a blood meal. Within the mosquito midgut, the male gametocyte undergoes a rapid nuclear division, producing 8 flagellated microgametes which fertilize the female macrogamete. The resulting ookinete traverses the mosquito gut wall and encysts on the exterior of the gut wall as a oocyst. Soon the oocyst ruptures, releasing hundreds of sporozoites into the mosquito body cavity where they eventually migrate to the mosquito salivary gland.
 * __ Range on Earth __**
 * __ Interesting facts __**



** Origins ** The closest relative of //Plasmodium falciparum// is //Plasmodium reichenowi//, a parasite of chimpanzees. //P. falciparum// and //P. reichenowi// are not closely related to the other //Plasmodium// species that parasitize humans, or indeed mammals generally. It has been argued that these two species originated from a parasite of birds. More recent analyses do not support this, however, instead suggesting that the ability to parasitize mammals evolved only once within the genus //Plasmodium//.


 * __ References __**
 * Roberts, L. S., & Janovy, J. (2000). //Gerald D. Schmidt & Larry S. Roberts' foundations of parasitology// (6th ed.). Boston: McGraw Hill.
 * Tongs, L. (2010). Malaria parasites (Apicomplexa, Haematozoea) and their relationships with their hosts. // World Health Organization //, //58//, 7.
 * Hartl, D. (2004, January 2). The origin of malaria: mixed messages from genetic... [Nat Rev Microbiol. 2004] - PubMed result. //National// //Center// //for Biotechnology Information//. Retrieved November 14, 2010, from []