Leishmaniasis as an emerging infection.

Leishmaniasis is a protozoan disease whose diverse clinical manifestations are dependent both on the infecting species of Leishmania and the immune response of the host. Transmission of the disease occurs by the bite of a sand fly infected with Leishmania parasites. Infection may be restricted to the skin in cutaneous leishmaniasis, limited to the mucous membranes in mucosal leishmaniasis, or spread internally in visceral leishmaniasis or kala azar. The overall prevalence of leishmaniasis is 12 million cases worldwide, and the global yearly incidence of all clinical forms approaches 2 million new cases (World Health Organization WHO/ LEISH/200.42, Leishmania/HIV Co-Infection in Southwestern Europe 1990-98: Retrospective Analysis of 965 Cases, 2000). In the last two decades, leishmaniasis, especially visceral leishmaniasis, has been recognized as an opportunistic disease in the immunocompromised, particularly in patients infected with human immunodeficiency virus.