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INTRODUCTION

KEY POINTS

  • Leishmaniasis is a chronic protozoan infection, described independently in 1903 by Leishman and Donovan.

  • There are at least 20 species of the protozoa that cause leishmaniasis in humans.

  • Certain species of leishmaniasis cause visceral leishmaniasis (eg, Leishmania infantum and Leishmania donovani), and others cause cutaneous disease (eg, Leishmania major and Leishmania tropica).

  • Emerging research has demonstrated that these species-specific presentations may not be absolute because some species can cause both types of infections.

  • The transmission of infection is primarily through the bite of sandflies of the genus Phlebotomus (Old World) or Lutzomyia (New World). Rarely, transmission can occur through shared syringes, by blood transfusion, or congenitally from mother to infant.

  • The sandfly usually bites at night and outdoors, although they have rarely been reported to bite during the day and indoors.

  • Leishmaniasis presents with lesions of the skin, mucous membranes, or internal organs, and the presentation is dependent on a number of factors including the infecting species of Leishmania, its virulence, number of parasites inoculated, site of bite, and the nutritional status and immune response of the host.

  • Diagnosis can be made clinically, particularly in endemic areas, or via microscopic examination of Giemsa-stained smear, leishmanin skin test, histologic examination of biopsy specimen, or serologic techniques including polymerase chain reaction technology.

  • Treatment modalities include topical or systemic chemotherapy, physical methods, and surgical intervention.

  • Recovery from infection confers lifelong immunity.

  • Prevention is always superior to treatment and cure.

Leishmaniasis is a chronic parasitic infection caused by inoculation of the Leishmania protozoan during the bite of an infected sandfly of the genus Phlebotomus in the Old World or Lutzomyia in the New World. The insect becomes infected when it bites infected humans or mammals such as rodents that harbor the Leishmania parasites.1 The sandfly usually bites at night and outdoors, but when disturbed in its habitat, it can bite during the day and indoors. However, on rare occasions, transmission can occur by shared syringes among intravenous drug users, by transfusion of infected blood, and congenitally from an infected mother to her infant.2

Four clinical forms of leishmaniasis exist: cutaneous, diffuse cutaneous, mucocutaneous, and visceral types. Clinical variants depend on the causative species of the Leishmania. There are at least 20 species of the protozoa that cause infections in humans, and some species cause visceral leishmaniasis (eg, Leishmania infantum and Leishmania donovani), whereas other species cause cutaneous disease (eg, Leishmania major and Leishmania tropica). Emerging research has shown that these species-specific presentations may not be absolute because some species can cause both types of infections. The virulence of the protozoan also determines the clinical outcome in the host. Additional determinants of clinical outcome include the number of parasites inoculated, the site of the bite, the nutritional status of the host, and integrity of the host immunity.

The diagnosis of leishmaniasis may be clinical, particularly in endemic areas. However, ...

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