DurgicalDurgical
EN
Open the app

Microbiology · Hemoflagellates (trypanosomes and Leishmania)

Leishmania (Viannia) panamensis, L. braziliensis and L. guyanensis !

  • Parasite
  • Exam priority: high

Parasites spread by sand flies in forested areas that cause chronic skin ulcers; some species later damage the nose and mouth.

Updated 2026-11-01

Also called: American cutaneous leishmaniasis, tegumentary leishmaniasis

At a glance

Shape
Oval amastigote in tissue; elongated flagellated promastigote in the vector and in culture
Family
Trypanosomatidae
Type
Intracellular flagellated protozoan (inside macrophages)
Stain
Giemsa: nucleus and rod-shaped kinetoplast
Size
Amastigote about 2 to 4 µm

Morphology

  • Small round to oval amastigote with a nucleus and a rod-shaped kinetoplast, inside macrophages.
  • Spindle-shaped promastigote with a free anterior flagellum, in the sand fly and in culture.
  • The species cannot be told apart by microscopy; culture with typing or PCR is needed.

Transmission

  • Bite of a female sand fly (Lutzomyia in the Americas) at dusk and night in forested and rural areas.
  • Occupational forest exposure: soldiers, farmers, miners and loggers.
  • Rarely congenital, by transfusion or needles.

Reservoir: Wild mammals (sloths, opossums, rodents); Dogs in some peridomestic foci

Vector: Female sand flies of the genus Lutzomyia.

Isolation precautions

What the care team adds to standard precautions.

  • Standard

Life cycle

  1. An infected sand fly bites and deposits metacyclic promastigotes in the skin.
  2. Macrophages engulf the promastigotes, which turn into amastigotes.
  3. Amastigotes multiply in the phagolysosome, burst the cell and infect new macrophages.
  4. Viannia species can spread through lymph or blood to the mucosa.
  5. A sand fly feeding on the lesion takes up macrophages with amastigotes.
  6. In the insect gut they become promastigotes, multiply and migrate to the proboscis.

Virulence factors

  • gp63 glycoprotein and lipophosphoglycan (LPG): binding to macrophages and complement resistance.
  • Survival inside the phagolysosome and blockade of macrophage activation.
  • A Th1 response with interferon-gamma controls infection; an exaggerated response destroys tissue (ulcer, mucosal lesion).
  • Leishmania RNA virus (LRV) in some Viannia strains, linked to more inflammation and treatment failure.

Diseases it causes

  • Localized cutaneous leishmaniasis: a round, painless ulcer with raised edges and a clean base, weeks after the bite. Leishmaniasis →
  • Mucosal leishmaniasis: destruction of the nasal septum, palate or larynx months or years later, mostly with L. braziliensis. Leishmaniasis →

Clinical picture

  • A papule that grows and ulcerates; the typical ulcer is round with an indurated, raised «picture-frame» border.
  • Nodular lymphangitis or regional lymphadenopathy may occur (more with L. panamensis and L. guyanensis).
  • Mucosal forms: congestion, nosebleeds, septal perforation and a «tapir nose».
  • The ulcer may heal on its own with a scar, but Viannia species carry a risk of mucosal disease.

Diagnosis

  • Direct Giemsa-stained smear from the ulcer edge: amastigotes in macrophages (the first-line test in Colombia).
  • Biopsy with hematoxylin-eosin and culture in biphasic NNN medium.
  • PCR to detect the parasite and identify the species.
  • Montenegro skin test as epidemiologic data; serology adds little in cutaneous disease.
  • Mucosal form: ENT exam, biopsy and serology, which does help here.

Treatment

Pentavalent antimonials (meglumine antimoniate, sodium stibogluconate) are the classic mainstay; alternatives include oral miltefosine, pentamidine isethionate, amphotericin B (conventional or liposomal) and local therapies (thermotherapy, cryotherapy, intralesional antimonial) in selected cases. Treating cutaneous disease from Viannia species lowers the risk of mucosal disease. Response varies by species.

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

In Pharmacology:

Prevention

  • Long sleeves, repellents and insecticide-treated nets when entering forest or sleeping in rural areas.
  • Protection of exposed groups such as soldiers on jungle operations.
  • Clearing brush and garbage around the home.

Vaccine: There is no human vaccine.

Test yourself

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

Which species causes most cutaneous leishmaniasis in Colombia?

Leishmania (Viannia) panamensis, followed by L. braziliensis and L. guyanensis in some regions.

What does the typical cutaneous leishmaniasis ulcer look like?

Round, painless, with an indurated raised border and a clean granular base, on exposed skin.

What is the first test to confirm cutaneous leishmaniasis?

A direct Giemsa-stained smear from the ulcer edge, looking for amastigotes inside macrophages.

Why are Viannia skin lesions treated even though they may heal on their own?

Because these species can spread to the mucosa and destroy the nose or mouth months or years later; treatment lowers that risk.

Which occupational group accounts for many cutaneous cases in Colombia?

Soldiers, because of jungle exposure; in 2023 they made up more than a fifth of cases.

Add to my cards (5)

← 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); Clinical Care of Leishmaniasis | Leishmaniasis | CDC (CDC, 2024); Leishmaniasis - PAHO/WHO | Pan American Health Organization (PAHO, 2025); Informe de Evento 2023 Leishmaniasis (Instituto Nacional de Salud (INS) Colombia, 2024).

Spotted a mistake?We are always improving for the community. Tell us what is wrong and our team will review it.Report a mistake

Representative model, for educational purposes only.