Plasmodium vivax
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224987852
2008-07-11T09:39:47Z
Johnsmith579
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/* Eradication Efforts in Korea */
{{Taxobox
| color = greenyellow
| name = ''Plasmodium vivax''
| image = Plasmodium_vivax_01.png
| image_width = 240px
| image_caption = Mature ''P. vivax'' [[trophozoite]]
| regnum = [[Protista]]
| phylum = [[Apicomplexa]]
| classis = [[Aconoidasida]]
| ordo = [[Haemosporida]]
| familia = [[Plasmodiidae]]
| genus = ''[[Plasmodium]]''
| species = '''''P. vivax'''''
| binomial = ''Plasmodium vivax''
| binomial_authority = [[Giovanni Battista Grassi|Grassi]] & [[Raimondo Feletti|Feletti]] 1890
}}
The [[parasite]] '''''Plasmodium vivax''''' is the most frequent and widely distributed cause of benign, but recurring (tertian), [[malaria]]. It is one of four species of parasite that commonly cause malaria infection in humans. It is less virulent than ''[[Plasmodium falciparum]]'', the deadliest of the four, and seldom fatal. ''P. vivax'' is passed on by the female ''[[Anopheles]]'' mosquito, since it is the only sex of the species that bites.
==Health==
===Epidemiology===
''Plasmodium vivax'' is found mainly in Asia, Latin America, and in some parts of Africa. ''P. vivax'' can cause death due to enlarged spleen, but more often it causes debilitating, but not deadly, symptoms.<ref name"cdc">{{cite web
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| title = Biology: Malaria (CDC malaria)
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| url = http://www.cdc.gov/malaria/biology/parasites/index.htm
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===Treatment===
[[Chloroquine]] remains the treatment of choice for ''vivax'' malaria, except in Indonesia's Irian Jaya ([[Western New Guinea]]) region and the geographically contiguous [[Independent State of Papua New Guinea|Papua New Guinea]], where chloroquine resistance is common (up to 20% resistance). When chloroquine resistance is common or when chloroquine is contraindicated, then [[artesunate]] is the drug of choice, except in the U.S. where it is not approved for use;<ref>{{cite journal | author=Pukrittayakamee S, ''et al.'' | title=Therapeutic responses to different antimalarial drugs in vivax malaria | journal=Antimicrob Agents Chemother | year=2000 | volume=44 | issue=6 | pages=1680–5 | doi=10.1128/AAC.44.6.1680-1685.2000 | pmid=10817728 }}</ref> [[mefloquine]] is a good alternative and in some countries is more readily available.<ref>{{cite journal | author=Maguire JD, Krisin, Marwoto H, Richie TL, Fryauff DJ, Baird JK | title=Mefloquine is highly efficacious against chloroquine-resistant ''Plasmodium vivax'' malaria and ''Plasmodium falciparum'' malaria in Papua, Indonesia | journal=Clin Infect Dis | year=2006 | volume=42 | issue=8 | pages=1067–72 | doi=10.1086/501357 }}</ref> [[Malarone|Atovaquone-proguanil]] is an effective alternative in patients unable to tolerate chloroquine.<ref>{{cite journal|author=Looareesuwan S, Wilairatana P, Glanarongran R, ''et al.''|journal=Trans Roy Soc Trop Med Hyg|year=1999|volume=93|pages=637–40
| doi = 10.1016/S0035-9203(99)90079-2
| title = Atovaquone and proguanil hydrochloride followed by primaquine for treatment of Plasmodium vivax malaria in Thailand}}</ref> [[Quinine]] may be used to treat ''vivax'' malaria but is associated with inferior outcomes.
32 to 100% of patients will relapse following successful treatment of ''P. vivax'' infection if a radical cure (eradication of liver stages) is not given.<ref>{{cite book|author=Wiselogle FY|title=A survey of antimalarial drugs, 1941–1945 (2 vols.)|location=Ann Arbor, Michigan|editor=J.W. Edwards(ed.)|year=1943}}</ref><ref>{{cite journal|author=Alving AS, Hankey DD, Coatney GR, ''et al.''|title=Korean vivax malaria. II. Curative treatment with pamaquine and primaquine|journal=Am J Trop Med Hyg|year=1953|volume=6|pages=9706}}</ref><ref>{{cite journal |author=Adak T, Sharma VP, Orlov VS|title=Studies on the Plasmodium vivax relapse pattern in Delhi, India|journal=Am J Trop Med Hyg|year=1998|volume=59|pages=1759}}</ref> Eradication of the liver stages is achieved by giving [[primaquine]], after checking the patients G6PD status to reduce the risk of haemolysis.<ref>{{cite journal|author=Baird JK & Hoffman SL|title=Primaquine therapy for malaria|journal=Clin Infect Dis|year=2004|volume=39|pages=1336–45|url=http://www.journals.uchicago.edu/CID/journal/issues/v39n9/33149/33149.html|doi=10.1086/424663|format={{deadlink}}}}</ref> Recently, this point has taken particular importance for the increased incidence of vivax malaria among travelers.<ref>{{cite journal|author=Rodriguez AJ & Franco-Paredes C|title=Acute Respiratory Distress Syndrome in Plasmodium vivax Malaria in Traveler Returning From Venezuela|journal=Journal of Travel Medicine|year=2006|volume=13|pages=325–6|url=http://www.blackwell-synergy.com/doi/abs/10.1111/j.1708-8305.2006.0064_1.x|doi=10.1111/j.1708-8305.2006.0064_1.x|format=abstract}}</ref>
===Eradication Efforts in Korea===
''P. vivax'' is the only indiginous [[malaria]] [[parasite]] on the Korean peninsula. In the years following the [[Korean War]] (1950-53), malaria-eradication campaigns successfully reduced the number of new cases of the disease in [[North Korea]] and [[South Korea]]. In 1979, [[World Health Organization]] declared the Korean vivax malaria-free but the disease unexpectedly re-emerged in the late 1990s and still persists today. Several factors contributed to the re-emergence of the disease, including reduced emphasis on malaria control after 1979, floods and famine in [[North Korea]], emergence of drug resistance and possibly [[global warming]]. Most cases are identified along the [[Korean Demilitarized Zone]]. As such, vivax malaria offers the two Koreas a unique opportunity to work together on an important health problem that affects both countries.<ref>http://www.koreatimes.co.kr/www/news/opinon/2008/05/160_24386.html For Re-Eradication of Malaria in Korea, Korea Times 05-19-2008</ref><ref>http://www.feer.com/international-relations/2008/july/Korean-War-Against-Malaria The Korean War Against Malaria, Far Eastern Economic Review 07-09-2008</ref>
==Biology==
''P. vivax'' can reproduce both asexually and sexually, depending on its life cycle stage.
Asexual forms:
* Immature trophozoites (Ring or signet-ring shaped), about 1/3 of the diameter of a RBC.
* Mature trophozoites: Very irregular and delicate (described as ''amoeboid''); many pseudopodial processes seen. Presence of fine grains of brown pigment (malarial pigment) or hematin probably derived from the haemoglobin of the infected red blood cell.
* [[wiktionary:schizont|Schizonts]] (also called meronts): As large as a normal red cell; thus the parasitized corpuslce becomes distended and larger than normal. there are about sixteen merozoites.
Sexual forms: Gametocytes: Round. The gametocytes of P. vivax are commonly found in the peripheral blood at about the end of the first week of parasitemia.
===Life Cycle===
The [[incubation period]] for the infection usually ranges from ten to seventeen days and sometimes up to a year. Persistent liver stages allow relapse up to five years after elimination of red blood cell stages and clinical cure.
====Human Infection====
====Liver Stage====
The ''P. vivax'' sporozoite enters a hepatocyte and begins its exoerythrocytic schizogony stage. This is characterized by multiple rounds of nuclear division without cellular segmentation. After a certain number of nuclear divisions, the parasite cell will segment and [[merozoites]] are formed.
There are situations where some of the sporozoites do not immediately start to grow and divide after entering the hepatocyte, but remain in a dormant, [[hypnozoite]] stage for weeks or months. The duration of latency is variable from one hypnozoite to another and the factors that will eventually trigger growth are not known; this explains how a single infection can be responsible for a series of waves of parasitaemia or "relapses".<ref name="1.4">{{cite web
| last =
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| title = Malaria eModule - Exo-Erythrocytic Stages
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| url = http://www.impact-malaria.com/FR/EPS/Formations_et_cours_internationaux/Formation_de_la_Liverpool_School_LSTMH/cours_liverpool/Unit_1/1_4.html
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| title = Malaria eModule - Hypnozoite and relapse
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| url = http://www.impact-malaria.com/FR/EPS/Formations_et_cours_internationaux/Formation_de_la_Liverpool_School_LSTMH/cours_liverpool/Unit_1/1_4_1.html
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====Erythrocytic Cycle====
[[Image:IEcycle.PNG|right|thumb|<ref name="bozdech">{{cite journal
| last = Bozdech
| first = Zbynek
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| title = The Transcriptome of the Intraerythrocytic Developmental Cycle of Plasmodium falciparum
| journal = PLoS Biology
| volume = 1
| issue = 1
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| date = August 18, 2003
| url = http://biology.plosjournals.org/perlserv/?request=get-document&doi=10.1371%2Fjournal.pbio.0000005
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''P. vivax'' preferentially penetrates young red blood cells (reticulocytes). In order to achieve this, merozoites have two proteins at their apical pole (PvRBP-1 and PvRBP-2). The parasite uses the Duffy blood group antigens (Fya and Fyb) as receptors to penetrate red blood cells. These antigens do not occur in the majority of humans in West Africa [phenotype Fy (a-b-)]. As a result ''P. vivax'' does not occur in West Africa.<ref name="vanden">{{cite web
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| title = Illustrated lecture notes on Tropical Diseases
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Microscopically, the parasitised [[red blood cell]] is up to twice as large as a normal red cell and [[Schüffner's stippling]] (also known as Schüffner's dots or Schüffner's granules) is seen on the infected cell's surface, the spotted appearance of which varies in color from light pink, to red, to red-yellow, as coloured with Romanovsky stains. The parasite within it is often wildly irregular in shape (described as "amoeboid"). [[wiktionary:schizont|Schizonts]] of ''P. vivax'' have up to twenty [[merozoite]]s within them. It is rare to see cells with more than one parasite within them. Merozoites will only attach to immature blood cell (reticulocytes) and therefore it is unusual to see more than 3% of all circulating erythrocytes parasitised.
====Sexual Stage====
====Mosquito Stage====
==Laboratory Considerations==
''P. vivax'' and ''[[Plasmodium ovale|P. ovale]]'' that has been sitting in [[EDTA]] for more than half-an-hour before the blood film is made will look very similar in appearance to ''[[Plasmodium malariae|P. malariae]]'', which is an important reason to warn the laboratory immediately when the blood sample is drawn so they can process the sample as soon as it arrives. Blood films are preferably made within half-an-hour of the blood being drawn and must certainly be made within an hour of the blood being drawn.
==References==
{{reflist}}
==External links==
*[http://www.map.ox.ac.uk Malaria Atlas Project]
[[Category:apicomplexa]]
[[Category:Malaria]]
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[[ps:پلازموډيم وايوېکس]]