Leishmaniasis

Overview:

• Definition: Leishmaniasis is a parasitic disease caused by protozoa of the genus Leishmania, transmitted by the bite of infected female phlebotomine sandflies.
• Forms: Three primary forms: cutaneous, mucocutaneous, and visceral (kala-azar), each with distinct clinical features.

2. Epidemiology:

• Geographic Distribution: Endemic in parts of Asia, Africa, the Americas, and the Mediterranean. High prevalence in regions with tropical and subtropical climates.
• Risk Factors: Poverty, malnutrition, deforestation, and urbanization increase exposure to sandflies.

3. Clinical Presentation:

• Cutaneous Leishmaniasis (CL):

  • caused by Leishmania tropica or Leishmania mexicana
  • Presents as non-healing ulcers or crusted lesion or nodules at the site of the sandfly bite.
  • Lesions are typically painless but can lead to disfiguring scars.
  • it is typically diagnosed by doing a punch biopsy from the edge of the lesion allowing for both histology and culture
  • cutaneous leishmaniasis acquired in South or Central America merits treatment due to the risk of mucocutaneous leishmaniasis whereas disease acquired in Africa or India can be managed more conservatively

  

  Cutaneous leishmaniasis - image shows an ulcerative erythematous plaque on the hand. Image used on license from Dermnet NZ

  

  

  Cutaneous leishmaniasis ulcer

• Mucocutaneous Leishmaniasis (MCL):

  • caused by Leishmania braziliensis
  • Progressive destruction of mucous membranes, particularly of the nose, mouth, and throat.
  • Often develops from untreated CL.

• Visceral Leishmaniasis (VL):

  • mostly caused by Leishmania donovani
  • occurs in the Mediterranean, Asia, South America, Africa
  • Systemic infection causing fever, sweats, rigors
  • massive splenomegaly. hepatomegaly
  • poor appetite*, weight loss
    • occasionally patients may report increased appetite with paradoxical weight loss
  • grey skin - 'kala-azar' means black sickness
  • pancytopenia ( secondary to hypersplenism), and hypergammaglobulinemia.
  • the gold standard for diagnosis is bone marrow or splenic aspirate
  • Fatal if untreated.

4. Diagnosis:

• Microscopy: Identification of amastigotes in tissue samples (skin, bone marrow, spleen).
• Culture: Promastigotes can be cultured from clinical specimens.
• Serology: Antibody tests useful in VL; however, cross-reactivity can occur.
• Molecular Tests: PCR for species identification and confirmation.

5. Management:

• Cutaneous Leishmaniasis:
  • Local therapy (cryotherapy, thermotherapy) or systemic treatments like antimonials, azoles, or miltefosine.
• Visceral Leishmaniasis:
  • First-line treatment includes liposomal amphotericin B or miltefosine.
  • Pentavalent antimonials (sodium stibogluconate) are also used, particularly in non-resistant areas.