Updated: 12/30/2018

Leishmaniasis

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Snapshot
  • A 38-year-old recent immigrant from Brazil comes into the clinic with a 4-month history of painless, ulcerated plaques on his left arm. He denies fever, fatigue, or weight loss. Physical exam revealed ulcers of varying sizes on the left arm, covered with a yellow-white fibrinous material. There are no mucosal lesions, pallor, lymphadenopathy, or hepatosplenomegaly. A complete blood count and liver function test were within normal limits. HIV serology, AFB for lepra bacilli, and serum VDRL were all negative. Histopathological exam of a skin biopsy showed amastigotes inside histiocytes and inflammatory cells. (Cutaneous leishmaniasis)
Introduction
  • Definition
    • a vector-borne disease transmitted by the sandfly and caused by Leishmania donovani, an intracellular protozoan parasite
  • Diseases
    • 2 clinical manifestations of leishmaniasis are
      • cutaneous leishmaniasis
      • visceral leishmaniasis ("kala-azar")
  • Epidemiology
    • incidence
      • rare in the United States and more common in Africa
  • Pathogenesis
    • the obligate intracellular parasite is transmitted to mammals via the sandfly
      • the parasite binds to macrophages of the reticuloendothelial system
        • within the macrophage (as amastigotes), the parasite undergoes binary fission and multiply until it lyses, releasing more parasite, which infect other cells, spreading the infection
      • coinfection with HIV
        • leishmaniasis accelerates the development of AIDS via
          • cummulative immunosuppression
          • stimulating the replication of the HIV virus
  • Prognosis
    • cutaneous leishmaniasis
      • typically self-resolves in 3-6 months without therapy
    • visceral leishmaniasis
      • a seriously progressive condition that can be lethal without treatment
      • if untreated, death can occur within 2 years
    • co-infection with HIV leads to a severe and rapidly progressive fatal outcome
Presentation
  • Symptoms
    • cutaneous leishmaniasis
      • cutaneous lesions
        • nontender ulceration
        • nonpruritic
      • diffuse cutaneous lesions can be seen in immunocompromised hosts
        • lesions may be plaques, ulcers, and nodules
        • diffuse lesions can appear similar to lepromatous leprosy
    • visceral leishmaniasis
      • darkening of the skin
      • fever 
      • weight loss
      • hepatosplenomegaly
      • pancytopenia
      • hypergammaglobulinemia
      • leukopenia
      • thrombocytopenia
Studies
  • Cutaneous leishmaniasis
    • confirming the diagnosis
      • Giemsa smear of a biopsy, dermal scraping, and/or needle aspirate
        • allows for direct visualization of the amastigote
      • culture
      • polymerase chain reaction (PCR)
  • Visceral leishmaniasis
    • confirming the diagnosis
      • Giemsa smear of a bone marrow aspiration (most commonly) or splenic puncture (high risk of hemorrhage)
        • allows for direct visualization of the amastigote
      • culture
      • PCR
Differential
  • Lepromatous leprosy
    • differentiating factors
      • skin biopsy and PCR will demonstrate Mycobacterium leprae organisms
      • results in sensory loss
Treatment
  • Conservative
    • observation
      • indication
        • in immunocompetent patients with strictly cutaneous (no visceral, mucosal, or systemic involvement) disease that is spontaneously healing and known to be caused by Leishmania species
  • Medical
    • liposomal amphotericin B
      • indication
        • first-line treatment for visceral leishmaniasis
Complications
  • Complications from pancytopenia
    • leukopenia
      • secondary bacterial infection
      • sepsis
    • anemia
      • fatigue
      • pallor
    • thrombocytopenia
      • bleeding

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