The Journal of Medical Microbiology, Vol 10, Issue 1 63-68, Copyright © 1977 by Society for General Microbiology
Airborne infection with Mycobacterium leprae in mice
R. J. Rees and A. C. McDougall
Although the portal of entry and mode of spread of M. leprae in human
leprosy are still uncertain, it is widely held that direct person-to-person
skin contact is important. This assumption has ignored the fact that
patients with highly bacilliferous leprosy have nasal as well as dermal
infection and that, since M. leprae is shed predominantly from the nose,
leprosy might be an airborne infection. The present study was designed to
investigate this possibility with mice exposed to airborne infection with
M. leprae. The conditions are described in which thymectomised-irradiated
CBA strain mice exposed to M. leprae aerosols sustained an immediate lung
retention of 1 X 10(5) bacteria. Fourteen to 24 months later, 33% (10 of
30) of the mice had countable numbers of acid-fast bacilli (greater than 2
X 10(4)) with the characteristics of M. leprae in one or more homogenates
prepared from ears, foot pads, nose or lungs. Evidence is presented from
the distribution of M. leprae that the infection had arisen from systemic
spresd of bacilli initially entering the lungs rather than from
multiplication of organisms locally retained there, or in the nose, at the
time of airborne infection. The relevance of these results to the possible
route of infection of leprosy in man is discussed.
