Leishmania

Classification

• Class – Mastigophora
• Order – Protomonadina

Epidemiology

Location

• Tropical and subtropical countries
• Mostly a disease of the developing world
• Reservoir of Leishmaniasis in India in acute visceral leishmaniasis

• 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.

• 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

• 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

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

Don’t Forget to Solve all the previous Year Question asked on Leishmania
Click Here to Start Quiz