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LEISHMANIA, image, india-political-map-3-849x1024, The-Reticuloendothelial…
LEISHMANIA
Life cycle
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The amastigote multiplies by binary fission, producing numerous daughter cells that distend the macrophage.
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When a vector sand fly feeds on an infected person, the amastigotes enter the insect along with its blood meal
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In the mid-gut of the sandfly, the amastigote elongates and develops into promastigote.
Laboratory diagnosis:
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Culture: N N N medium (described by Novy, MacNeal and Nicolle)
The smears are stained by Leishman, Giemsa, or Wright's stain
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Detection of antibodies: (IFAT, CIEP and DAT)
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Lelshmanin skin test (Montenegro test), it is the confirmatory test
Pathogenicity
In the spleen, liver and bone marrow particularly, the amastigotes multiply enormously
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Clinical features
Skin becomes dry, rough and darkly pigmented
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History and distribution
Of the new cases, 90% are found in the Indian subcontinent and Sudan and Brazil.
Sir William Leishman in 1900 observed the parasite in spleen smears of a soldier who died of "dumdum fever" or kala-azar contracted at Dum Dum, Calcutta. Leishman reported this finding from London in 1903.In the same year, Donovan also reported the same parasite in spleen smears of patients from Madras.
At present, the disease has established its endemicity in Bihar, West Bengal, UP, Tamil Nadu and Karnataka.
Morphology
Promastigote
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The promastigotes, which are initially short, oval or pear shaped
forms, subsequently become long spindle-shaped cells.
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The flagellum is single, delicate and measures 15- 28 μm.
Giemsa or Leishman -stained film s show pale blue cytoplasm with a pink nucleus and bright red kinetoplast.
Amastigote
It is an ovoid or rounded cell, about 2- 4 μmin size.
It is typically intracellular, being found inside macrophages monocytes, neutrophils, or endothelial cells.
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Lying at the right angles to nucleus, is the red or purple-stained kinetoplast. In well-stained preparations, the kinetoplast can be seen consisting of a parabasal body and a dot-like blepharoplast. Vacuole is also present.
Habitat
The amastigote (LD body) of L. donovani is found in the reticuloendothelial system. They are found mostly within the the macrophages in the spleen, liver and bone marrow.
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