BIOLOGICAL BEHAVIOR OF LEISHMANIA-AMAZONENSIS ISOLATED FROM HUMANS WITH CUTANEOUS, MUCOSAL, OR VISCERAL LEISHMANIASIS IN BALB C MICE/

Leishmania amazonensis causes a wide spectrum of disease in humans. In this study, we evaluated BALB/c mice infected with five strains of L. amazonensis isolated from patients with either cutaneous, mucosal, or visceral leishmaniasis. Mice infected with cutaneous and mucosal isol ates developed ulcerating footpad lesions with parasite-loaded macroph ages and extensive tissue destruction. Skin metastases, early dissemin ation of parasites to the spleen, and high anti-Leishmania antibody le vels were also noted. Mice infected with L. amazonensis strains isolat ed from patients with visceral disease had a controlled infection, wit h small footpad lesions with mononuclear cell infiltration, few infect ed macrophages, and granuloma formation. They had no skin metastases, delayed dissemination of the parasite to the spleen, lower levels of I gG and higher levels of IgG2a against L. amazonensis. These findings d emonstrate an unexpected resistance of BALB/c mice to the infection wi th L. amazonensis isolated from patients with visceral leishmaniasis. This resistance seems to be due to differences in these parasites that may be related to the altered course of the disease in humans and in isogenic BALB/c mice.