• Clinical science

Leishmaniasis

Summary

Leishmaniasis is a parasitic disease caused by protozoans of the Leishmania genus, which are transmitted by infected phlebotomine sand flies. Depending on the parasite subtype and the strength of the host's immune system, the disease manifests in a cutaneous or visceral form. Cutaneous leishmaniasis is characterized by skin ulcers. The most important clinical manifestation of visceral leishmaniasis is kala-azar (Hindi for “black fever”), which presents with fever, weight loss, hepatosplenomegaly, and immunosuppression. Leishmaniasis is diagnosed by microscopic visualization of macrophages containing amastigotes in blood smears or tissue. Local treatment (cryotherapy, topical paromomycin) suffices for most cases of cutaneous leishmaniasis. Visceral leishmaniasis requires systemic treatment with amphotericin B.

Epidemiology

  • Distribution: endemic in the Mediterranean region, Africa, India, southwest and central Asia, South and Central America
  • Incidence (worldwide):
    • Visceral: 200,000–400,000 infections/year
    • Cutaneous: 700,000–1,200,000 infections/year

References:[1][2]

Epidemiological data refers to the US, unless otherwise specified.

Etiology

  • Pathogen: Leishmania donovani (protozoan)
  • Transmission
    • Vector: phlebotomine sandflies
    • Reservoir: mammals (especially dogs, humans, and rodents)

References:[2]

Cutaneous leishmaniasis

Clinical features

Diagnostics

Treatment

Prognosis

Without treatment, localized cutaneous leishmaniasis heals over months to years with a scar or keloid. Reactivation may occur years after initial symptoms resolve.

References:[3][4][5]

Visceral leishmaniasis

Clinical features

  • Incubation period: 2–6 months
  • Many patients are asymptomatic.
  • Kala-azar (hindi for “black fever,” in reference to the darkening of the skin it can cause)

Diagnostics

Treatment

Kala-azar is highly fatal without treatment!

References:[3][6][7]