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Leishmania (view source)

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==Overview==

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''Leishmania spp.'' are intracellular parasites of [[Macrophage|macrophages]] from the same family as ''[[Trypanosoma]] spp.''. These organisms parasitise human, dogs and wild animals throughout southern Europe, Africa, Asia and South America. The infection is transmitted by [[Psychodidae|sandflies]]. Infection can cause both cutaneous and visceral disease. Three types of ''Leishmania spp.'' are described;

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''Leishmania spp.'' are intracellular parasites of [[Macrophage|macrophages]] from the same family as ''[[Trypanosoma]] spp.''. These organisms parasitise human, dogs and wild animals throughout southern Europe, Africa, Asia and South America. The infection is transmitted by [[Psychodidae|sandflies]]. Infection can cause both cutaneous and visceral disease. Clinical disease cause by ''Leishmania'' is termed [[Leishmaniosis]]. Three types of ''Leishmania spp.'' are described;

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# '''~~Hypoplaria~~''' - found in lizards that ingest the sandfly intermediate host. Development occurs in the hindgut of the fly.

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# '''Hypopylaria''' - found in lizards that ingest the sandfly intermediate host. Development occurs in the hindgut of the fly.

# '''Peripylaria''' - found in mammals and lizards, development occurs in the fore- and hindgut of the fly.

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# '''~~Suprpylaria~~''' - found only in mammals transmitted by the bite of a sandfly, development occurs in the fore- and midgut of the fly.

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# '''Suprapylaria''' - found only in mammals transmitted by the bite of a sandfly, development occurs in the fore- and midgut of the fly.

==Recognition==

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==Pathogenesis==

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Infection with ''Leishmania'' can produce either cutaneous or viscreal disease as the infected macrophages proliferate in foci. There is a very long incubation period from infection to pathology, which can take years and therefore many infected dogs either never become symptomatic or remain so for a long period of time.

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Infection with ''Leishmania'' can produce either cutaneous or viscreal disease as the infected macrophages proliferate in foci. There is a very long incubation period from infection to pathology, which can take years and therefore many infected dogs either never become symptomatic or remain so for a long period of time. Even once an animal has been treated for leishmaniasis it is not uncommon for clinical symptoms to recur after a lengthy period of remission. Information on the clinical signs and treatment for disease caused by leishmania can be found on the [[Leishmaniosis]] page.

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The cutaneous form of the disease produces areas of ulceration on the pinnae of the [[Ear - Anatomy & Physiology|ears]], eyelids or on the [[Lips - Anatomy & Physiology|lips]]. These ucerations can also be seen between the digits of the dogs paw. This is a parasitic infection of the [[Parasitic skin infections - Pathology#Protozoa|skin]].

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The viscreal form causes a chronic wasting condition where generalised excema can be seen. Hair is lossed from around the eyes giving the animal a 'spectacled' appearance. These symptoms are accompanied by an intermitted fever and some generalized lymphadenopathy.

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Even once an animal has been treated for leishmaniasis it is not uncommon for clinical symptoms to recur after a lengthy period of remission.

==Epidemiology==

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Although the UK is not home to any species of sand fly, leishmaniasis is being observed more frequently in the domestic dog population. This has largely been attributed to the increase in the number of animals that travel to areas of Europe and north Africa where the disease is endemic. These animals often acquire the disease whilst abroad but may not show clinical signs until they have been back in the UK for a considerable length of time. There has however been some evidence to show that clost contact between dogs can spread the disease, though this method of transmission is much less common.

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~~==Diagnosis==~~

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Definitive diagnosis of Leishmaniasis requires combining observation of the clinical signs discussed above and the demonstration of ''Leishmania'' orgnisms in the animal. In the cutaneous disease this may be done by microscopic analysis of skin scrapings from the animals. For diagnosis of the visceral disease samples of joint fluid, [[Lymph Nodes - Anatomy & Physiology|lymph node]] or [[Bone Marrow - Anatomy & Physiology|bone marrow]] biopsies may all contain macrophages that have been infected by the organisms.

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~~==Treatment and Control==~~

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Control of ''Leishmania'' is difficult due to the large environmental pool and the sand flies that transmit the disease. One method is to prevent the sand flies from biting dogs by using collars inpregnated with [[Ectoparasiticides|insecticides]] or repellents. These have a limited effect and do not guarantee the safety of the animal. Destruction of infected and stray dogs will decrease the pool from which sand flies may obtain the parasite but this is often morally difficult and due to the infection of wildlife does not stop spread completely.

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Chemotherapy can be used to treat dogs with leishmaniasis, however this will not cure the infection completely. It may send the infection, but as mentioned earlier it is not uncommon for clinical sign to return later in the dogs life. There are also many risks to chemotherapy such as suppression of the immune system, not to mention the expense of prolonged treatment.

[[Category:Tropical Protozoa]]

[[Category:To_Do_-_NickJ]]

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