Clinical Spectrum of Leishmaniasis

The clinical manifestations of leishmaniasis depend on com­ plex interactions between the virulence characteristics of the infecting Leishmania species and the immune responses of its host. The result is a spectrum of disease ranging from localized skin lesions to diffuse involvement of the reticuloendothelial system. Human disease has traditionally been divided into three major clinical syndromes: visceral, cutaneous, and mucosal leishmaniasis; however, a number of variants exist. Further­ more, a single Leishmania species can produce more than one clinical syndrome, and each syndrome is caused by multiple species. The true incidence and prevalence of leishmaniasis is uncer­ tain because many cases go undiagnosed or unreported in areas where the infection is endemic. In 1993, the World Health Organization estimated that 350 million people worldwide were at risk for infection. The incidence of cutaneous leishmaniasis has been estimated to be 1.0-1.5 million cases per year, and