This 28-year-old white male presented to the dermatology clinic complaining of sores on his arms. On examination, two lesions measuring 0.7 to 1.5 cm in diameter were present on his right arm. These lesions showed central ulceration and a raised, indurated margin surrounding the ulcer. The lesions had developed over approximately one month. The patient had applied topical antibiotics, which had no effect. The patient had recently returned from a World Wildlife Fund study site in the Amazon region of Brazil, where he had been conducting field research in the rain forest. A biopsy was taken from the raised edge of one of the ulcers.
Leishmania parasites are transmitted by the bite of an infected sand fly. Sand flies are common in Central and South America as well as in the Middle East, Southeast Asia, and Africa. Travelers can help prevent infection by using insect repellent -- especially at night when sand flies are out biting.
Leishmania amastigotes grow inside macrophage phagolysosomes. They have special glycoconjugates on their surface which help them resist attach by complement, help them bind to and be phagocytosed by macrophages, and help protect them from free radical damage inside the phagolysosomes. Leishmania amastigotes also have a special proton-transporting ATPase that helps them survive the high acidity of the phagolysosome.
Patients can also get mucocutaneous leishmaniasis or visceral leishmaniasis depending on the species of leishmania organism causing the infection.
- If the biopsy had shown only a granulomatous inflammatory response but no organisms, what other infectious diseases would be in the differential diagnosis?
Blastomyces, Mycobacterium ulcerans, Sporothrix schenckii.
- eMedicine Medical Library: Leishmaniasis
- eMedicine Medical Library: Leishmaniasis in Emergency Medicine
- eMedicine Medical Library: Dermatologic Manifestations of Leishmaniasis
- Merck Manual: Leishmaniasis
- Choi CM, Lerner EA. Leishmaniasis as an emerging infection. J Investig Dermatol Symp Proc 2001 Dec;6(3):175-82.