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→Leishmania
==''Leishmania''==
==''Leishmania''==
*''Leishmania'' spp. are intracellular parasites of [[Macrophage|macrophages]]
*Are closely related to ''Trypanosoma'' spp.
*Cause diseases in humans, dogs and wild animals
*Present in southern Europe, Africa, Asia and South America
'''Life Cycle'''
'''Life Cycle'''
*Transmitted by blood sucking [[Biting Flies#Psychodidae|sand flies]]
**''Phlebotomus'' spp. in the Old World
**''Lutzomyia'' spp. in the New World
*The amastigote (morphological form) in found in vertebrate [[Macrophage|macrophages]]
*Ingested by [[Biting Flies#Psychodidae|sand fly]] during feeding
**Transforms in [[Insecta|insect]] gut
*Multiplies and migrates to [[Insecta|insect]] proboscis
**Innoculated during feeding
**Can be transmitted percutaneously if [[Biting Flies#Psychodidae|sand fly]] crushed on skin
*Invades [[Macrophage|macrophages]] and reverts to amastigote
'''Pathogenesis'''
'''Pathogenesis'''
*Infection of vertebrate host
**Produces foci of proliferating ''Leishmania''-infected [[Macrophage|macrophages]] in skin ('''cutaneous''') or internal organs ('''visceral''')
''Leishmania'' involved in [[Parasitic skin infections - Pathology#Protozoa|skin infections]]
*Very long incubation periods
**Months to years
*Many infected dogs are asymptomatic
*Cutaneous form
**Produces areas of ulceration on pinnae of ears
*Visceral form causes chronic wasting condition
**Generalised eczema
***Loss of hair around eyes producing 'spectacle' effect
**Intermittent fever
**Generalised lymphadenopathy
*Involved in [[Parasitic skin infections - Pathology#Protozoa|skin infections]]
'''Epidemiology'''
'''Epidemiology'''
*Disease dependent on [[Biting Flies#Psychodidae|sand fly]] vectors
**E.g. Common in dogs around the Mediterranean coast, foci around southern Europe and around Madrid
*Reservoirs of infection
**E.g. Wild animals such as rodents and stray dogs
*Mechanisms of transmission
**Direct contact
**[[Biting Flies#Psychodidae|sand fly]] bite
*Leishmaniasis in British dogs
**Susceptible to infection if exposed whilst abroad in endemic areas as have no immunity
**No [[Biting Flies#Psychodidae|sand flies]] in Britain but dogs have become infected whilst in contact with infected imported animals
'''Diagnosis'''
'''Diagnosis'''
*Demonstrate ''Leishmania'' organisms
**In skin scraping or smears
**In [[Lymph Nodes - Anatomy & Physiology|lymph node]] or [[Bone Marrow - Anatomy & Physiology|bone marrow]] biopsies
'''Treatment and Control'''
'''Treatment and Control'''
*Chemotherapy
**Prolonged treatment, expensive, suppresses infection
**Does not cure infection
*Prevent [[Biting Flies#Psychodidae|sand flies]] biting
**Collars, sprays containing [[Ectoparasiticides|insecticide]] with repellent effect
*Destruction of infected and stray dogs
**[[Biting Flies#Psychodidae|Sand flies]] biting infected dogs may spread the disease to to other dogs, humans and wildlife
**There is a slight possibility of transmission to humans by direct contact