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| [[Image:Malaria.jpg|thumb|left|250px|A ''Plasmodium'' sporozoite traverses the cytoplasm of a mosquito midgut epithelial cell in this false-color [[electron micrograph]].]]
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| ==Causes==
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| === Malaria parasites ===
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| Malaria is caused by [[protozoa]]n [[parasite]]s of the genus ''[[Plasmodium]]'' (phylum [[Apicomplexa]]). In humans malaria is caused by ''[[Plasmodium falciparum|P. falciparum]]'', ''[[Plasmodium malariae|P. malariae]]'', ''[[Plasmodium ovale|P. ovale]]'', and ''[[Plasmodium vivax|P. vivax]]''. '' P. vivax'' is the most common cause of infection, responsible for about 80 % of all malaria cases. However, ''P. falciparum'' is the most important cause of disease, and responsible for about 15% of infections and 90% of deaths.<ref>{{cite journal | author = Mendis K, Sina B, Marchesini P, Carter R | title = The neglected burden of Plasmodium vivax malaria. | url=http://www.ajtmh.org/cgi/reprint/64/1_suppl/97.pdf | journal = Am J Trop Med Hyg | volume = 64 | issue = 1-2 Suppl | pages = 97-106 | year = 2001 | pmid = 11425182}}</ref> Parasitic ''Plasmodium'' species also infect birds, reptiles, monkeys, chimpanzees and rodents.<ref>{{cite journal | author = Escalante A, Ayala F | title = Phylogeny of the malarial genus Plasmodium, derived from rRNA gene sequences. | url=http://www.pnas.org/cgi/reprint/91/24/11373 | journal = Proc Natl Acad Sci U S A | volume = 91 | issue = 24 | pages = 11373-7 | year = 1994 | pmid = 7972067}}</ref> There have been documented human infections with several [[Wiktionary:simian|simian]] species of malaria, namely ''[[Plasmodium knowlesi|P. knowlesi]]'', ''P. inui'', ''P. cynomolgi''<ref>{{cite book | last=Garnham | first=PCC | date=1966 | title=Malaria parasites and other haemosporidia | publisher=Blackwell Scientific Publications|Location=Oxford }}</ref>, ''P. simiovale'', ''P. brazilianum'', ''P. schwetzi'' and ''P. simium''; however these are mostly of limited public health importance. Although avian malaria can kill chickens and turkeys, this disease does not cause serious economic losses to poultry farmers.<ref>Investing in Animal Health Research to Alleviate Poverty. International Livestock Research Institute. Permin A. and Madsen M. (2001) [http://www.ilri.cgiar.org/InfoServ/Webpub/fulldocs/investinginanimal/Book1/media/PDF_Appendix/Appendix8.pdfLiterature Appendix 2: review on disease occurrence and impact (smallholder poultry)]. Accessed 29 Oct 2006</ref> However, since being accidentally introduced by humans it has decimated the endemic birds of Hawaii, which evolved in its absence and lack any resistance to it.<ref>{{cite journal |author=Atkinson CT, Woods KL, Dusek RJ, Sileo LS, Iko WM |title=Wildlife disease and conservation in Hawaii: pathogenicity of avian malaria (''Plasmodium relictum'') in experimentally infected iiwi (''Vestiaria coccinea'') |journal=Parasitology |volume=111 Suppl |issue= |pages=S59-69 |year=1995 |pmid=8632925 |doi=}}</ref>
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| == Mosquito vectors and the ''Plasmodium'' life cycle ==
| | #REDIRECT [[Plasmodium]] |
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| The parasite's primary (definitive) hosts and transmission [[vector (biology)|vector]]s are female [[mosquito]]es of the ''[[Anopheles]]'' genus. Young mosquitoes first ingest the malaria parasite by feeding on an infected human carrier and the infected ''[[Anopheles]]'' mosquitoes carry ''Plasmodium'' [[sporozoite]]s in their [[salivary gland]]s. A mosquito becomes infected when it takes a blood meal from an infected human. Once ingested, the parasite [[gametocytes]] taken up in the blood will further differentiate into male or female [[gametes]] and then fuse in the mosquito gut. This produces an [[ookinete]] that penetrates the gut lining and produces an [[oocyst]] in the gut wall. When the oocyst ruptures, it releases [[sporozoites]] that migrate through the mosquito's body to the salivary glands, where they are then ready to infect a new human host. This type of transmission is occasionally referred to as anterior station transfer.<ref>{{cite journal | author = Talman A, Domarle O, McKenzie F, Ariey F, Robert V | title = Gametocytogenesis: the puberty of Plasmodium falciparum. | journal = Malar J | volume = 3 | issue = | pages = 24 | year = | id = PMID 15253774}}</ref> The sporozoites are injected into the skin, alongside saliva, when the mosquito takes a subsequent blood meal.
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| Only female mosquitoes feed on blood, thus males do not transmit the disease. The females of the ''[[Anopheles]]'' genus of mosquito prefer to feed at night. They usually start searching for a meal at dusk, and will continue throughout the night until taking a meal. Malaria parasites can also be transmitted by [[blood transfusion]]s, although this is rare.<ref>{{cite journal | author = Marcucci C, Madjdpour C, Spahn D | title = Allogeneic blood transfusions: benefit, risks and clinical indications in countries with a low or high human development index. | journal = Br Med Bull | volume = 70 | issue = | pages = 15-28 | year = | id = PMID 15339855}}</ref>
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| ==References==
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| {{reflist|3}}
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