Leishmaniasis is a disease caused by an intracellular protozoa parasite transmitted by the bite of a female sandfly (Phlebotomus species). [1] The clinical spectrum of leishmaniasis ranges from a self-resolving, localized cutaneous ulcer to widely disseminated progressive lesions of the skin, to a mutilating mucocutaneous disease, and even to a lethal systemic illness that affects the reticuloendothelial system.
Classic Leishmania major lesion from a case in Iraq shows a volcanic appearance with rolled edges.
The predominant mode of leishmaniasis transmission is a sandfly's bite.
Leishmania donovani is one of the main Leishmania species that infects humans.
This condition affects as many as 12 million people worldwide, with 900,000 to 1.3 million new cases each year. The global incidence of leishmaniasis has increased in recent years due to increased international leisure- and military-related travel, human alteration of vector habitats, and concomitant factors that increase susceptibility, such as infection with human immunodeficiency virus (HIV) and malnutrition. With the exception of Australia, the Pacific Islands, and Antarctica, the parasites have been identified throughout large portions of the world.
Old World localized cutaneous leishmaniasis located on the trunk of a soldier stationed in Kuwait. This lesion was a 3-cm by 4-cm nontender ulceration that developed over the course of 6 months at the site of a sandfly bite. The patient reported seeing several rats around his encampment.
Old World cutaneous leishmaniasis located on the right arm of the same soldier stationed in Kuwait. This 2-cm by 3-cm lesion was located at the exposed area where the sleeve ended. Note the satellite lesions.
The taxonomy of Leishmania organisms is complex, and no single categorization is generally accepted.
Taxonomy of some of the medically important protozoans showing the relative relationship of the Kinetoplastida parasites generally, and Leishmania specifically.
The 2 simplest and most widely used disease categorization systems are based on clinical disease and geographic occurrence, as follows [2, 3, 1] :
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Clinical disease: The primary clinical forms of leishmaniasis are cutaneous, mucocutaneous, and visceral disease; cutaneous manifestations can be further subdivided into localized, diffuse (disseminated), recidivans, and post–kala-azar dermal leishmaniasis
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Geographic occurrence: Old World leishmaniasis is caused by Leishmania species found in Africa, Asia, the Middle East, the Mediterranean, and India, and it produces cutaneous or visceral disease; New World leishmaniasis is caused by Leishmania species found in Central America and South America, and it produces cutaneous, mucocutaneous, and visceral disease. Diagnosis of leishmaniasis often is difficult because of the small size of the protozoa sequestered within macrophages of the skin, bone marrow, and reticuloendothelial system.
Therapy has long been a challenge in the more severe forms of the disease, and it is made more difficult by the emergence of drug resistance. No effective vaccine for leishmaniasis is available.