Table 1.

Detection of M. leprae in the respiratory tract of C57BL/6 mice after intranasal challenge with 10⁷ bacilli

Time of infection	Total no. of mice	No. of mice infected with visible acid-fast bacilli	Infected tissues and cells (Ziehl-Nielssen staining)	H&E staining result
4 h	6	2	Acid-fast bacilli in terminal bronchioles and circumjacent lung tissue; bacilli were observed inside epithelial cells and macrophages	No visible lesions
4 days	6	1	Infected macrophages in lung tissue	No visible lesions
10 days	4	0		No visible lesions
20 days	4	0		No visible lesions