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Old World cutaneous Leishmania (L. major, L. tropica, L. aethiopica)

  • Parasite
  • Exam priority: medium

Leishmania of Africa, the Middle East and Asia spread by sand flies. They cause skin ulcers that heal slowly and leave scars.

Updated

Also called: oriental sore, Aleppo boil, Baghdad boil, Old World cutaneous leishmaniasis

Quick facts

Type
Parasite · Hemoflagellates (trypanosomes and Leishmania)
Gram / shape
Amastigote
Spread
Bite of female Phlebotomus sand flies · L · L
Causes
Localized cutaneous leishmaniasis
Treatment
Simple sores may be left to heal or treated locally

At a glance

Shape
Amastigote: small oval body with nucleus and rod-shaped kinetoplast
Family
Trypanosomatidae
Type
Intracellular protozoan (hemoflagellate); amastigote in macrophages, promastigote in the sand fly
Stain
Giemsa of a slit-skin smear or biopsy from the ulcer edge
Size
Amastigote about 2 to 4 µm

Morphology

  • Amastigotes inside macrophages of the skin, with a nucleus and a kinetoplast.
  • Promastigotes with a front flagellum in the sand fly gut and in culture.
  • Species cannot be told apart by microscopy; molecular tests are needed.

Transmission

  • Bite of female Phlebotomus sand flies, mostly from dusk to dawn.
  • L. major: zoonotic, from desert rodents (gerbils, sand rats) through Phlebotomus papatasi.
  • L. tropica: mainly anthroponotic, from person to person in towns through Phlebotomus sergenti.
  • L. aethiopica: in the highlands of Ethiopia and Kenya, with hyraxes as reservoir.

Reservoir: Desert rodents (L. major); Humans (L. tropica); Rock and tree hyraxes (L. aethiopica)

Vector: Phlebotomus sand flies (the Old World counterpart of Lutzomyia); they are 2 to 3 mm long and pass through ordinary mosquito nets.

Isolation precautions

What the care team adds to standard precautions.

  • Standard

Life cycle

  1. A female Phlebotomus injects promastigotes into the skin while feeding.
  2. Macrophages engulf them and they turn into amastigotes.
  3. Amastigotes multiply inside macrophages and infect new ones in the dermis.
  4. Another sand fly takes up infected cells with its blood meal.
  5. In the fly gut they become promastigotes and move to the mouthparts, ready for the next bite.

Virulence factors

  • Survival inside the macrophage phagolysosome.
  • The host's cellular (Th1) response decides the picture: a good response heals the sore; an anergic response causes diffuse disease.
  • An exaggerated response with few parasites causes leishmaniasis recidivans.

Diseases it causes

  • Localized cutaneous leishmaniasis (oriental sore): papule that becomes a painless crusted ulcer with raised edges on exposed skin; heals in months to a year with a scar. Leishmaniasis →
  • Leishmaniasis recidivans (mainly L. tropica): new papules at the edge of an old scar, for years. Leishmaniasis →
  • Diffuse cutaneous leishmaniasis (L. aethiopica): many non-ulcerating nodules full of parasites in anergic patients; hard to treat. Leishmaniasis →

Clinical picture

  • Incubation from weeks to months; lesions on face, arms and legs.
  • L. major sores tend to be moist and heal faster; L. tropica sores are drier and last longer.
  • Travelers, soldiers and aid workers return with a sore that does not heal; displaced populations have spread it, as in the Syrian conflict.
  • Old World species, unlike L. braziliensis, rarely cause mucosal disease.

Diagnosis

  • Slit-skin smear, scraping or biopsy from the active edge, stained with Giemsa: amastigotes.
  • Culture and PCR; species identification guides treatment.
  • Serology is not useful for cutaneous disease.

Treatment

Simple sores may be left to heal or treated locally (cryotherapy, heat therapy, topical paromomycin, intralesional pentavalent antimonials). Complex, multiple or facial lesions get systemic treatment (pentavalent antimonials such as meglumine antimoniate, miltefosine or liposomal amphotericin B), chosen by species; L. tropica responds less well.

Drug class only; doses and regimens are set by the clinician from the current guideline.

In Pharmacology:

Prevention

  • Avoiding outdoor activity from dusk to dawn; long clothing and repellents.
  • Permethrin-treated nets, clothing and screens; fine-mesh nets.
  • Rodent control near homes (L. major) and early treatment of patients (L. tropica).

Test yourself

Think of the answer, then tap the question to see it.

Which sand fly genus transmits Old World leishmaniasis?

Phlebotomus (Lutzomyia is the American genus).

Which Old World species is zoonotic from rodents and which is mainly spread between people?

L. major is zoonotic (desert rodents); L. tropica is mainly anthroponotic in towns.

What is leishmaniasis recidivans?

New papules around the scar of an old sore that keep appearing for years, mainly with L. tropica.

Which species causes diffuse cutaneous leishmaniasis in East Africa?

L. aethiopica, in patients with a weak cellular immune response.

Why identify the species in a traveler with cutaneous leishmaniasis?

Because treatment choice and the risk of mucosal disease depend on the species.

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Connections

← Back to the group: Hemoflagellates (trypanosomes and Leishmania)

Educational content on microorganisms; not a treatment guide and no substitute for a health professional's advice. No doses are given.

Sources: CDC - DPDx - Leishmaniasis (CDC, 2024); Leishmaniasis | CDC Yellow Book (CDC, 2025); Cutaneous Leishmaniasis and Conflict in Syria (Emerging Infectious Diseases (CDC), 2016); Leishmaniasis (DermNet, 2024).

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Representative model, for educational purposes only.