Difference between revisions of "Leishmania"
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[[Image:Leishmania Life Cycle.jpg|thumb|right|150px|Leishmania Life Cycle - Wikimedia Commons]] | [[Image:Leishmania Life Cycle.jpg|thumb|right|150px|Leishmania Life Cycle - Wikimedia Commons]] | ||
[[Image:Leishmania donovani.jpg|thumb|right|150px|''Leishmania donovani'' in bone marrow cell - Dr. L.L. Moore, Jr.]] | [[Image:Leishmania donovani.jpg|thumb|right|150px|''Leishmania donovani'' in bone marrow cell - Dr. L.L. Moore, Jr.]] | ||
− | [[Image:Leishmania tropica.jpg|right|thumb|150px|''L. tropica'' < | + | [[Image:Leishmania tropica.jpg|right|thumb|150px|''L. tropica'' <br> Yutaka TsutsumiWikiMedia Commons]] |
− | ''Leishmania spp. | + | *''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 | ||
+ | |||
+ | *Can cause both cutaneous and visceral diseases | ||
+ | |||
+ | '''Recognition''' | ||
+ | *Ovoid shaped | ||
+ | |||
+ | *Possesses a rod-shaped kinetoplast | ||
+ | |||
+ | *Has a rudimentary flagellum which does not project beyond the cell margin | ||
+ | |||
+ | *After the amastigote has transformed into a promastigote inside the [[Biting Flies#Psychodidae|sand fly]], the kinetoplast is situated in the posterior of the body | ||
+ | |||
+ | '''Life Cycle''' | ||
+ | *Transmitted by blood sucking [[Psychodidae|sand flies]] | ||
+ | **''Phlebotomus'' spp. in the Old World | ||
+ | **''Lutzomyia'' spp. in the New World | ||
+ | |||
+ | *The amastigote (morphological form) is found in vertebrate [[Macrophage|macrophages]] | ||
+ | |||
+ | *Ingested by [[Psychodidae|sand fly]] during feeding | ||
+ | **Transforms in [[Insecta|insect]] gut | ||
+ | |||
+ | *Multiplies and migrates to [[Insecta|insect]] proboscis | ||
+ | **Inoculated during feeding | ||
+ | **Can be transmitted percutaneously if [[Psychodidae|sand fly]] crushed on skin | ||
+ | |||
+ | *Invades [[Macrophage|macrophages]] and reverts to amastigote | ||
+ | |||
+ | *Multiplies by binary fission | ||
− | + | '''Pathogenesis''' | |
− | ''Leishmania | + | *Infection of vertebrate host |
+ | **Produces foci of proliferating ''Leishmania''-infected [[Macrophage|macrophages]] in skin ('''cutaneous''') or internal organs ('''visceral''') | ||
− | + | *Very long incubation period | |
− | + | **Months to years | |
− | + | *Many infected dogs are asymptomatic | |
− | + | *Cutaneous form | |
+ | **Produces areas of ulceration on pinnae of [[Ear - Anatomy & Physiology|ears]], eyelids or on the [[Lips - Anatomy & Physiology|lips]] | ||
− | + | *Visceral form causes chronic wasting condition | |
− | + | **Generalised eczema | |
+ | ***Loss of hair around eyes producing 'spectacle' effect | ||
+ | **Intermittent fever | ||
+ | **Generalised lymphadenopathy | ||
− | + | *Long periods of remission followed by recurrence of clinical signs is not uncommon in infections | |
− | + | *Involved in [[Parasitic skin infections - Pathology#Protozoa|skin infections]] | |
− | |||
− | + | '''Epidemiology''' | |
+ | *Disease dependent on [[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 | |
− | + | **[[Psychodidae|sand fly]] bite | |
+ | **Rarely through direct contact | ||
− | + | *Leishmaniasis in British dogs | |
− | + | **Susceptible to infection if exposed whilst abroad in endemic areas as have no immunity | |
+ | **No [[Psychodidae|sand flies]] in Britain but dogs have become infected whilst in contact with infected imported animals | ||
− | + | '''Diagnosis''' | |
+ | *Demonstrate ''Leishmania'' organisms | ||
+ | **In skin scraping or smears | ||
+ | **In joint fluid, [[Lymph Nodes - Anatomy & Physiology|lymph node]] or [[Bone Marrow - Anatomy & Physiology|bone marrow]] biopsies | ||
− | + | '''Treatment and Control''' | |
− | + | *Chemotherapy | |
− | + | **Prolonged treatment, expensive, suppresses infection | |
− | + | **Does not cure infection | |
− | |||
− | |||
+ | *Prevent [[Psychodidae|sand flies]] biting | ||
+ | **Collars, sprays containing [[Ectoparasiticides|insecticide]] with repellent effect | ||
− | + | *Destruction of infected and stray dogs | |
+ | **[[Psychodidae|Sand flies]] biting infected dogs may spread the disease to other dogs, humans and wildlife | ||
+ | **There is a slight possibility of transmission to humans by direct contact | ||
+ | |||
+ | |||
+ | In dogs | ||
+ | *disseminated disease of the monocyte-macrophage system | ||
+ | *protozoa; genus ''Leishmania'' | ||
+ | *increased travel means clinincal disease may be acquired in endemic areas but now presents to veterinarians in non-endemic areas | ||
+ | *lymph node aspirates contain macrophages with organisms | ||
− | |||
[[Category:Tropical Protozoa]] | [[Category:Tropical Protozoa]] | ||
− | [[Category: | + | |
− | + | [[Category:To_Do_-_Parasites]] |
Revision as of 11:00, 22 July 2010
This article has been peer reviewed but is awaiting expert review. If you would like to help with this, please see more information about expert reviewing. |
- Leishmania spp. are intracellular parasites of macrophages
- Are closely related to Trypanosoma spp.
- Cause diseases in humans, dogs and wild animals
- Present in southern Europe, Africa, Asia and south America
- Can cause both cutaneous and visceral diseases
Recognition
- Ovoid shaped
- Possesses a rod-shaped kinetoplast
- Has a rudimentary flagellum which does not project beyond the cell margin
- After the amastigote has transformed into a promastigote inside the sand fly, the kinetoplast is situated in the posterior of the body
Life Cycle
- Transmitted by blood sucking sand flies
- Phlebotomus spp. in the Old World
- Lutzomyia spp. in the New World
- The amastigote (morphological form) is found in vertebrate macrophages
- Multiplies and migrates to insect proboscis
- Inoculated during feeding
- Can be transmitted percutaneously if sand fly crushed on skin
- Invades macrophages and reverts to amastigote
- Multiplies by binary fission
Pathogenesis
- Infection of vertebrate host
- Produces foci of proliferating Leishmania-infected macrophages in skin (cutaneous) or internal organs (visceral)
- Very long incubation period
- Months to years
- Many infected dogs are asymptomatic
- Visceral form causes chronic wasting condition
- Generalised eczema
- Loss of hair around eyes producing 'spectacle' effect
- Intermittent fever
- Generalised lymphadenopathy
- Generalised eczema
- Long periods of remission followed by recurrence of clinical signs is not uncommon in infections
- Involved in skin infections
Epidemiology
- Disease dependent on 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
- sand fly bite
- Rarely through direct contact
- Leishmaniasis in British dogs
- Susceptible to infection if exposed whilst abroad in endemic areas as have no immunity
- No sand flies in Britain but dogs have become infected whilst in contact with infected imported animals
Diagnosis
- Demonstrate Leishmania organisms
- In skin scraping or smears
- In joint fluid, lymph node or bone marrow biopsies
Treatment and Control
- Chemotherapy
- Prolonged treatment, expensive, suppresses infection
- Does not cure infection
- Prevent sand flies biting
- Collars, sprays containing insecticide with repellent effect
- Destruction of infected and stray dogs
- Sand flies biting infected dogs may spread the disease to other dogs, humans and wildlife
- There is a slight possibility of transmission to humans by direct contact
In dogs
- disseminated disease of the monocyte-macrophage system
- protozoa; genus Leishmania
- increased travel means clinincal disease may be acquired in endemic areas but now presents to veterinarians in non-endemic areas
- lymph node aspirates contain macrophages with organisms