|Description:||This 1962 photograph depicted a man’s extended left arm, the volar surface of which displayed a leishmanial lesion due to his leishmaniasis infection. Leishmaniasis is transmitted by the bite of female phlebotomine sand flies. The sand flies inject the infective stage, promastigotes, during blood meals. Promastigotes that reach the puncture wound are phagocytized by macrophages and transform into amastigotes. Amastigotes multiply in infected cells and affect different tissues, depending in part on the Leishmania species. This originates the clinical manifestations of leishmaniasis. Sand flies become infected during blood meals on an infected host when they ingest macrophages infected with amastigotes. In the sand fly's midgut, the parasites differentiate into promastigotes, which multiply and migrate to the proboscis.|
Human leishmanial infections can result in 2 main forms of disease, cutaneous leishmaniasis, as was the case here, and visceral leishmaniasis (kala-azar). The factors determining the form of disease include leishmanial species, geographic location, and immune response of the host. Cutaneous leishmaniasis is characterized by one or more cutaneous lesions on areas where sand flies have fed. Persons who have cutaneous leishmaniasis have one or more sores on their skin. The sores can change in size and appearance over time. They often end up looking somewhat like a volcano, with a raised edge and central crater. A scab covers some sores. The sores can be painless or painful. Some people have swollen glands near the sores (for example, in the armpit if the sores are on the arm or hand).