Leishmaniasis

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Leishmaniasis Basics - Sandfly's Sting

  • Protozoan disease by Leishmania spp.; transmitted by female Phlebotomus sandfly bite.
  • Key Indian Species:
    • L. donovani (Visceral Leishmaniasis/Kala-azar)
    • L. tropica (Cutaneous Leishmaniasis)
  • Vector: Phlebotomus argentipes (main vector for VL in India).
  • Life Cycle:
    • Sandfly: Ingests amastigotes → develop to promastigotes (infective).
    • Human: Promastigotes injected → transform to amastigotes in macrophages (diagnostic).
  • Endemic (India): Bihar, Jharkhand, West Bengal, E. Uttar Pradesh. Life cycle of the Phlebotomus sandfly

⭐ Diagnostic stage: Amastigotes (Leishman-Donovan bodies) within human macrophages.

Disease Spectrum - Skin & Spleen Saga

  • Visceral Leishmaniasis (Kala-azar / Black Fever)

    • Agent: L. donovani (India).
    • Incubation: 2-6 months (variable).
    • Classic Triad:
      • Prolonged fever (>2 weeks).
      • Massive splenomegaly (± hepatomegaly).
      • Progressive weight loss, cachexia.
    • Lab: Pancytopenia (↓Hb, ↓WBC, ↓Platelets), polyclonal hypergammaglobulinemia (↑IgG).
    • Post-Kala-azar Dermal Leishmaniasis (PKDL):
      • Hypopigmented macules, papules, nodules, plaques.
      • Appears 6 months - 2 years (or more) post-VL treatment.
      • Important reservoir of infection.
  • Cutaneous Leishmaniasis (CL)

    • Agents: L. tropica, L. major.
    • Forms:
      • Localized (LCL): "Oriental Sore", "Delhi Boil". Most common.
      • Diffuse (DCL): Anergic, widespread nodules.
      • Recidivans (LR): Chronic, relapsing at scar edge.
    • Lesion: Starts as papule → nodule → painless ulcer with raised, indurated "volcano-like" border; may be dry or crusted.
    • Sites: Exposed areas (face, limbs).
    • Cutaneous Leishmaniasis Ulcer
  • Mucocutaneous Leishmaniasis (MCL)

    • Rare in India (primarily New World: L. braziliensis).
    • If occurs with L. donovani, involves destructive lesions of nasal, oral, pharyngeal mucosa.

⭐ > Amastigotes (Leishman-Donovan bodies) are found within macrophages in tissue samples (spleen, bone marrow, skin).

Spotting the Parasite - Detective Work

Giemsa stain of Leishmania donovani in macrophages

  • Visceral Leishmaniasis (VL):
    • Definitive Dx: LD bodies (Giemsa stain) in aspirates (spleen - highest yield, bone marrow, lymph node).
    • Serology: rK39 strip test (rapid), DAT, ELISA.
    • Molecular: PCR (high sensitivity, species ID).
  • Cutaneous/Mucocutaneous (CL/MCL):
    • Microscopy: LD bodies in slit-skin smear/tissue imprint (Giemsa).
    • Biopsy for:
      • Histopathology (LD bodies).
      • Culture (NNN medium).
    • Molecular: PCR (species ID).
    • Montenegro Skin Test (Leishmanin):
      • Measures CMI; induration ≥5mm = positive.
      • Positive: Most CL (not DCL), cured VL. Negative: Active VL, DCL.

⭐ The rK39 antigen-based immunochromatographic test is a highly sensitive and specific rapid diagnostic for Visceral Leishmaniasis, crucial in resource-limited settings.

Fighting Back - Drugs & Defense

Treatment:

  • Visceral Leishmaniasis (VL / Kala-azar):
    • First-line: Liposomal Amphotericin B (LAmB) (e.g., 10 mg/kg single IV dose - India); Miltefosine (2.5 mg/kg/day PO, 28 days, ⚠️ Teratogenic); Paromomycin IM.
    • Combination therapy (LAmB + Miltefosine or LAmB + Paromomycin) for ↑efficacy, ↓resistance, esp. in endemic areas.
    • Sodium Stibogluconate (SSG): Marked resistance in Indian subcontinent.
  • Cutaneous Leishmaniasis (CL):
    • Local: Paromomycin ointment, intralesional SSG, cryotherapy, heat therapy.
    • Systemic (severe/unresponsive): Miltefosine, SSG (if sensitive), azoles (e.g., Ketoconazole).
  • Post-Kala-azar Dermal Leishmaniasis (PKDL):
    • Miltefosine or LAmB (often prolonged course, e.g., 12 weeks for Miltefosine).

⭐ Miltefosine: First effective and exclusively oral drug for visceral leishmaniasis.

Prevention & Control:

  • Vector (Sandfly) Control: Indoor Residual Spraying (IRS) (e.g., DDT, synthetic pyrethroids), environmental hygiene.
  • Personal Protection: Insecticide-treated nets (ITNs), repellents (e.g., DEET).
  • Early case detection & complete treatment.
  • Health education on disease transmission & personal protection measures.

High‑Yield Points - ⚡ Biggest Takeaways

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Practice Questions: Leishmaniasis

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In a patient presented with a fever and a positive filarial antigen test, what is the next appropriate method of management?

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Flashcards: Leishmaniasis

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Border of the crusted ulcer of old world Leishmaniasis (oriental sore) often has an erythematous rim and is called as _____ sign

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Border of the crusted ulcer of old world Leishmaniasis (oriental sore) often has an erythematous rim and is called as _____ sign

Volcano

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