Leishmania
531084
30539972
2008-06-11T16:54:21Z
194.80.231.145
{{ébauche|protiste|médecine}}
{{Taxobox protiste | ''Leishmania'' | Leishmania donovani 01.png | Leishmania donovani}}
{{Taxobox phylum | Euglenozoa}}
{{Taxobox classe | Kinetoplastea}}
{{Taxobox ordre | Trypanosomatida}}
{{Taxobox famille | Trypanosomatidae}}
{{Taxobox genre protiste (auteur) | Leishmania | [[Ronald Ross|Ross]], [[1903]]}}
{{Taxobox taxons protiste | Voir texte}}
{{Taxobox fin}}
'''''Leishmania''''' est un {{b genre}} de [[protiste]] proche des [[trypanosome]]s, et est un [[Parasite (médecine)|parasite]] responsable d'une maladie, la [[leishmaniose]]. <!--It is spread through [[sandfly|sandflies]] of the genus ''[[Phlebotomus]]'' in the Old World, and of the genus ''[[Lutzomyia]]'' in the New World. They primary hosts is a [[vertebrate]]; ''Leishmania'' commonly infects [[hyrax]]es, [[canid]]s, [[rodent]]s, and [[human]]s. ''Leishmania'' currently affects 12 million people in 88 countries.
''Leishmania'' cells have two morphological forms: promastigote (with an anterior flagellum) in the insect host, and amastigote (without flagella) in the vertebrate host. Infections are regarded as cutaneous, mucocutaneous, or visceral:
* Cutaneous (localized and diffuse) infections appear as obvious skin reactions. The most common is the Oriental Sore (caused by Old World species ''L. major'', ''L. tropica'', and ''L. aethiopica''). In the New World, the most common culprits are ''L. mexicana'' and ''L. (Viannia) braziliensis''. Cutaneous infections are most common in [[Afghanistan]], [[Brazil]], [[Iran]], [[Peru]], [[Saudi Arabia]] and [[Syria]].
* Mucocutaneous (espundia) infections will start off as a reaction at the bite, and can go [[metastasis]] into the mucous membrane and become fatal. Mucocutaneous infections are most common in [[Bolivia]], [[Brazil]] and [[Peru]].
* Visceral infections are often recognized by fever, weight loss, swelling of the liver and spleen, and [[anemia]]. They are known by many local names, of which the most common is probably ''Kala azar'' [http://homepages.uel.ac.uk/D.P.Humber/akhter/dis.htm] [http://www.bartleby.com/61/51/K0005100.html], and are caused exclusively by species of the ''L. donovani'' complex (''L. donovani'', ''L. infantum'' syn. ''L. chagasi''). Visceral infections are most common in [[Bangladesh]], [[Brazil]], [[India]], [[Nepal]] and [[Sudan]].
An important aspect of the ''Leishmania'' protozoan is its [[glyconjugate]] layer of liphosphoglycan (LPG). This is held together with a phosphoinosite membrane anchor, and has a tripartite structure consisting of a lipid domain, a neutral hexasaccharide, and a phosphrorylated galactose-mannose, with a termination in a neutral cap. Not only do the little unfriendlies not develop post-phlebotomus digestion but, it is thought to be essential to oxidative bursts, thus allowing passage for infection. Chararacteristics of digestion include an [[endosome]] fusing with a [[lysosome]], releasing acid [[hydrolase]]s which degrade [[DNA]], [[RNA]], proteins and [[carbohydrates]].
Treatments of the disease generally involve a solution containing [[antimony]], which is toxic. A solution which breaks down the LPG is also a form of treatment being looked at. Those who feel they are infected should seek immediate attention. Transmission is mainly through the bite of sand flies but also through needle-sharing by drugs users. Most at risk are humans infected with [[HIV]], canines and rodents.
The origins of ''Leishmania'' are a well thought out subject. Theories vary. One proposes an African orgin, with migration to the Americas. Another migration from the Americas to the Old World about 15My ago, accross the [[Bering Strait]] land bridge. Another proposes a palaearctic origin. Such migrations would entail migration of vector and reservoir or successive adaptations along the way. A more recent migration is that of ''L. infantum'' from Mediterranean countries to Latin America (there named ''L. chagasi''), since European colonization of the New World, where the parasites picked up its current New World vectors in their respective ecologies. This is the cause of the epidemics now evident. One recent New World epidemic concerns foxhounds in the USA.
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==Espèces==
Il y a de nombreuses espèces différentes, parmi lesquelles :
* ''[[Leishmania aethiopica]]''
* ''[[Leishmania amazonensis]]''
* ''[[Leishmania arabica]]''
* ''[[Leishmania archibaldi]]''
* ''[[Leishmania aristedes]]''
* ''[[Leishmania (Viannia) braziliensis]]''
* ''[[Leishmania chagasi]]''
* ''[[Leishmania (Viannia) colombiensis]]''
* ''[[Leishmania deanei]]''
* ''[[Leishmania donovani]]''
* ''[[Leishmania enriettii]]''
* ''[[Leishmania equatorensis]]''
* ''[[Leishmania forattinii]]''
* ''[[Leishmania garnhami]]''
* ''[[Leishmania gerbili]]''
* ''[[Leishmania (Viannia) guyanensis]]''
* ''[[Leishmania herreri]]''
* ''[[Leishmania hertigi]]''
* ''[[Leishmania infantum]]''
* ''[[Leishmania killicki]]''
* ''[[Leishmania (Viannia)lainsoni]]''
* ''[[Leishmania major]]''
* ''[[Leishmania mexicana]]''
* ''[[Leishmania (Viannia) naiffi]]''
* ''[[Leishmania (Viannia) panamensis]]''
* ''[[Leishmania (Viannia) peruviana]]''
* ''[[Leishmania (Viannia) pifanoi]]''
* ''[[Leishmania (Viannia) shawi]]''
* ''[[Leishmania turanica]]''
* ''[[Leishmania tropica]]''
* ''[[Leishmania venezuelensis]]''
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==Liens externes==
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{{portail médecine}}
[[Catégorie:Protiste (nom scientifique)]]
[[Catégorie:Parasite]]
[[Catégorie:Euglenozoa]]
[[ca:Leishmània]]
[[de:Leishmanien]]
[[en:Leishmania]]
[[es:Leishmania]]
[[ja:リーシュマニア]]
[[ka:ლეიშმანია]]
[[pt:Leishmania]]
[[ru:Лейшмании]]
[[tr:Leishmania]]
[[ar:ليشمانيا]]