Leishmania

Leishmania


Classification

  • Class – Mastigophora
  • Order – Protomonadina
Leishmaniasis
  • Leishmania donovani  (complex) (VL)
  • Leishmania tropica (CL)
  • Leishmania major (CL)
  • Leishmania aethiopica (CL)
  • Leishmania Mexicana (Complex) (CL)
  • Leishmania brazilliensis (complex) (MCL)
  • Leishmania peruriana

Epidemiology

  • Location
  • Tropical and subtropical countries
  • Mostly a disease of the developing world
  • Reservoir of Leishmaniasis in India in acute visceral leishmaniasis
Forms
Amastigote forms
  • Seen in human infections
  • Seen mainly in the cells of reticuloendothelial system located in:
  •  liver
  • spleen
  • bone marrow
  • peripheral blood

Leishman-Donovan bodies:

  • Intracellular Amastigotes microscopically seen. 
  • Within blood and spleen monocytes
  • Less commonly, in circulating neutrophils and in aspirated tissue macrophages

Morphology

  • Non motile and round to oval 2-4 µm long.
  • Nucleus is round to oval.
  • The nucleus is red and the kinetoplast is bright red on Leishman stain
  • A clear unstained space is present alongside the axoneme called the vacuole. 
  • The parasite has the blepharoplast and axoneme.
  • Amastigote form also has a parabasal body.
Promastigote forms
  • Seen in the gut of sand fly Phlebotomus argentipes.
  • It is also seen when grown in laboratory on artificial culture media.
  • Morphology:
  • It is a spindle shaped structure measuring 15-20 um by 1-2 um.
  • It has a flagellum arising from the axoneme and coming out of the anterior end.
  • Blepheroplast and a vacuole in the anterior end
  • Nucleus is round to oval and central in location.
  • The nucleus is red and the kinetoplast is bright red on Leishman stain
Lifecycle
  • Development in sandfly
  • Penetration of promastigote in host macrophages
  • Conversion of promastigotes into amastigote
  • Rupture of infected macrophages
  • Ingestion of amastigote by another macrophage
  • Multiplication
  • Repetition

Culture 

  • L. donovani can be cultured in N.N.N. (Novy, Macneal and Nicolle) medium.
  • In N.N.N. medium amastigote form changes into promastigote form.

Transmission

  • phlebotomine sand flies

Clinical Manifestations

Initial Infection

  • Similar in all species
  • Inoculation of promastigotes
  • Inflammation & chemotaxis
  • Receptor mediated phagocytosis
  • Promastigote Amasitgote

Leishmania donovani 

  • Causes a visceral disease called Kala azar.
  • Hepatosplenomegaly
  • Pancytopenia
  • Intermittent fever. 
  • There is associated anaemia, cachexia, loss of weight.
  •  Dry skin, brittle hair and pigmentation of skin. 
  • Diarrhoea, dysentery. 
  • Oedema is seen due to hypoalbuminemia. 
  • Immune-complex-mediated mesangio-proliferative glomerulonephritis seen
  • Post kala azar dermal leishmaniasis:
  • Develops in about 10 percent of kala – azar patients after complete treatment .
  • Visceral infection disappears but the skin infection persists.
  1. Depigmented macules- Trunk and extremities (face less common)
  2. Erythematous patches- On nose, cheeks, and chin, often having a butterfly distribution (butterfly erythema)
  3. Yellowish pink nodule on face
  • Leishmania tropica:
  • Causes Oriental sore (cutaneous leishmaniasis) On the skin

  • Which becomes dry there may appear solitary or multiple ulcerating papules.
  • Healing occurs with scarification. 
  • Leishmania brazilensis
  • Espundia 
  • Muco cutaneous leishmaniasis/nasopharyngeal leishmaniasis

Diagnosis 

  • Blood smear
  • stained with Giemsa or Leishman’s stains
  • Direct visualization of the amastigotes
  • In aspirates of bone marrow, spleen, liver or lymph nodes, makes the diagnosis
  • PCR assay
  • Aldehyde test
  • Supportive hematological tests.

Treatment

Conservative

  • protection from sand fly bites
  • stay indoors from dusk to dawn (when sand flies are most active)
  • wear long pants and shirt for extra skin coverage
  • insect repellent 
  • skin sores will usually heal on their own

Pharmacologic

  • Drug used for Leishmaniasis (Kala azar)
  • Sodium stibogluconate (DOC)
  • Pentamidine
  • Amphotericin B
  • Ketoconazole
  • Miltefosine
  • Paromomycin
  • Allopurinol.
  • Miltefosine
  • For visceral and cutaneous
  • Fluconazole
  • Effective in treating cutaneous leishmaniasis
Exam Question
 

Epidemiology

  • Location
  • tropical and subtropical countries
  • mostly a disease of the developing world
  • Reservoir of Leishmaniasis in India in acute visceral leishmaniasis
Forms
Amastigote forms
  • Seen in human infections
  • Leishman-Donovan bodies:
  • Intracellular Amastigotes microscopically seen. 
  • Wthin blood and spleen monocytes
  • Less commonly, in circulating neutrophils and in aspirated tissue macrophages
Promastigote forms
  • Seen in the gut of sand fly Phlebotomus argentipes.
  • It is also seen when grown in laboratory on artificial culture media.
  • It is a spindle shaped structure measuring 15-20 um by 1-2 um.
  • It has a flagellum arising from the axoneme and coming out of the anterior end.
  • Blepheroplast and a vacuole in the anterior end
  • Nucleus is round to oval and central in location.
  • The nucleus is red and the kinetoplast is bright red on Leishman stain
Culture 
  • L. donovani can be cultured in N.N.N. (Novy, Macneal and Nicolle) medium.
  • In N.N.N. medium amastigote form changes into promastigote form.

Transmission

  • phlebotomine sand flies

Clinical Manifestations

  • Leishmania donovani 
  • Causes a visceral disease called Kala azar.
  •  Hepatosplenomegaly
  • Immune-complex-mediated mesangio-proliferative glomerulonephritis seen
  • Leishmania tropica:
  • Causes Oriental sore (cutaneous leishmaniasis) On the skin
  • Post kala azar dermal leishmaniasis:
  •  Leishmania brazilensis
  • Espundia 
  • muco cutaneous leishmaniasis/nasopharyngeal leishmaniasis

Diagnosis 

  • Blood smear
  • stained with Giemsa or Leishman’s stains
  • Direct visualization of the amastigotes
  • In aspirates of bone marrow, spleen, liver or lymph nodes, makes the diagnosis
  • Aldehyde test
  • Supportive hematological tests.

Treatment

Pharmacologic

  • Drug used for Leishmaniasis (Kala azar) – 
  • Sodium stibogluconate (DOC)
  • Pentamidine
  • Amphotericin B
  • Ketoconazole
  • Miltefosine
  • Paromomycin
  • Allopurinol.
  • miltefosine
  • for visceral and cutaneous
  • fluconazole
  • effective in treating cutaneous leishmaniasis
Don’t Forget to Solve all the previous Year Question asked on Leishmania

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