Cutaneous Leishmaniasis Overview

Leishmaniasis

• Leishmaniasis is a zoonotic, chronic inflammatory disease affecting skin, mucous membranes, or viscera.
• It's caused by obligate intracellular flagellate protozoan parasites.

Objectives

• Students will identify the general features of the Leishmania genus.
• Students will list the causative agents of leishmaniasis.
• Students will list the vectors responsible for transmitting leishmaniasis.
• Students will discuss the epidemiology, habitat, life cycle, pathogenesis, and clinical aspects of leishmaniasis.
• Students will discuss the laboratory diagnosis of leishmaniasis.
• Students will discuss the treatment, prevention, and control of leishmaniasis.

Leishmaniasis Description

• Leishmaniasis is a zoonotic chronic inflammatory disease of the skin, mucous membranes, or viscera.
• Caused by obligate intracellular flagellate protozoan parasites.

History

• William Leishman identified visceral leishmaniasis in Dum-Dum village, Calcutta, India (1903) - also known as Dum-Dum fever.
• Charles Donovan (1903) identified the parasite and named the Leishmania-Donovan (LD body)

Transmission

• Leishmaniasis is transmitted by female sand flies.
• New World leishmaniasis is transmitted by Lutzomyia sand flies.
• Old World leishmaniasis is transmitted by Phlebotomus sand flies.

Classification

• Visceral leishmaniasis (kala-azar) from the L. donovani complex—includes species infecting Africa, Asia, and Europe.
  • L. donovani, L. infantum, L. chagasi.
• Cutaneous leishmaniasis from the L. tropica complex—affects Africa, Asia, and Europe.
  • L. tropica minor, L. tropica major
• Mucocutaneous leishmaniasis from L. braziliensis complex affects South America.
  • L. braziliensis
• L. mexicana complex affects South America.
  • L. mexicana

Visceral Leishmaniasis (Kala-azar) Description

• The L. donovani complex causes visceral leishmaniasis in the old world.
• The primary reservoirs are dogs and cats.
• Transmission occurs through the bite of female sandflies of the genus Phlebotomus.
• The parasite develops from promastigote to amastigote.
• Amastigotes multiply in macrophages.
• The main endemic area in Sudan is in the eastern part of the country, stretching from the western part of the White Nile to the Sudanese-Ethiopian border in the east.

Life Cycle

• The parasite has two forms:
  • Intracellular, non-flagellated amastigotes (Leishman-Donovan bodies). These are found in mammals
  • Promastigotes
• Sand flies transmit the infective promastigote stage.
• Promastigotes transform into amastigotes after phagocytosis by macrophages.
• Amastigotes reproduce and fill the macrophages' cytoplasm.

Promastigote

• Found in the insect midgut. Its elongated, motile, and flagellated form.

Amastigote

• Found in the mammalian reticuloendothelial system.
• Round or oval in shape. Non-motile.
• Thin cell membrane and a dense nucleus.
• A rod-shaped kinetoplast within the cytoplasm.

Visceral Leishmaniasis Pathogenesis & Clinical Picture

• Leishmanioma, often seen in African cases.
• Intermittent fever, hepatosplenomegaly, generalized lymphadenopathy, and diarrhea.
• Bone marrow depletion and pancytopenia.
• Secondary infections contribute to loss and death.
• Reverse albumin/globulin ratio (hypergammaglobulinemia)
• Glomerulonephritis due to immune complex deposition.

Visceral Leishmaniasis Kala-Azar Skin

• Hyperpigmentation (black fever).
• Butterfly erythema on the nose and cheeks.
• Post kala-azar dermal leishmaniasis: Maculopapular hypo-pigmented areas starting on the face.
• Response to antimony treatment and immune-mediated factors increased amastigotes, making patients reservoirs.

Diagnosis

• History and clinical picture (e.g., typical ulcer).
• Direct diagnosis by aspiration or biopsy from ulcer margins. Amastigotes are found in macrophages.
• Culture (NNN media) yields promastigotes.
• Immunodiagnosis using Montenegro leishmanin test (intradermal test, induration in 2-3 days).
• Serology (ELISA, IFA).
• PCR

Treatment

• First-line treatment for visceral leishmaniasis: Pentavalent antimonial drug --Sodium stibogluconate (SSG)—effective in Sudan.
• Amphotericin B deoxycholate or pentamidine.
• Allopurinol in AIDS cases.
• Splenectomy for recurrent cases.

Management of Cutaneous Leishmaniasis

• Single lesions heal spontaneously in 5-12 months.
• Treat with antibiotics, if the ulcer is secondarily infected.
• Larger or non-healing cutaneous forms require pentavalent antimonials (e.g., sodium stibogluconate).

Control

• Treat all cases.
• Control animal reservoirs.
• Control sandfly populations.

Test your knowledge about cutaneous leishmaniasis, including its progression after infection, diagnostic methods, and management strategies. Explore key aspects such as the Montenegro test and treatment options for varying forms of this infection.