First lesion in experimental armadillo leprosy.

Eighteen armadillos were infected intravenously with 10(8) M. leprae and 10 intracutaneously with 10(7) M. leprae. Among those which developed disseminated disease, a nodule at the site of inoculation was the first lesion noticed in 14 of the 16 infected intravenously and 4 of the 4 infected intradermally. It is possible that in human leprosy the first sign of infection is localized proliferation of M. leprae at the site of entry, and even nodule formation in lepromatous patients. It may be important to search for asymptomatic swelling or keloid-like lesions in skin or in nasal mucosa while screening a population for early leprosy.