RESUMO
The intranasal route is one of the main routes of Mycobacterium leprae infection and there is paucity of information regarding the mode of spread of the pattern. The adherence of M. leprae to the nasal mucosa, its trapping within the sinuses of the head, and its fate after entry into the host was studied using mouse model. A comparison of the adherence profile of M. leprae and Mycobacterium tuberculosis showed that while larger numbers of M. tuberculosis were demonstrated within lungs, greater numbers of M. leprae were present within the sinuses of the head. Adherence of M. leprae to the nasal mucosa was dependent on surface integrity since opsonization and heat killing resulted in decreased numbers of M. leprae in the nasal sinuses and a greater amount entering the lungs. The adherence appeared to the independent of the viability of the bacilli, as similar numbers of formalin-fixed, rifampicin -treated and viable M. leprae entered the lungs in the initial stages. However the numbers of rifampicin-treated M. leprae in the nasal sinuses were 12-fold lower than the numbers of viable M. leprae. These results indicated that both viability and surface integrity were important in the entry of M. leprae and it's consequent dissemination.