In a previous paper1 I traversed to some extent the ground indicated by this contribution, but, as probably few Americans will see that paper in print, I take the liberty of borrowing from it to some extent as affording a text and illustration of what follows.
There is agreement among authorities that the sputum expectorated by consumptives, and becoming dried and powdered, constitutes the principal means by which the tuberculous infection is extended; the precise manner in which the recipient acquires it—whether by inhalation, ingestion or inoculation—being of secondary importance, but that pathogenic lodgment must necessarily take place in one or more of these several ways. The seriousness of the situation is increased by the fact ascertained by competent observers that the vitality of the infecting germ retained within doors may endure unimpaired for several months.
This particular form of infection, then, being capable of, and adapted to, dissemination
HOMAN G. THE DANGER OF DUST AS A CAUSE OF TUBERCULOSISIN DOMESTIC HOUSEHOLDS, CLUBS, HOTELS, SCHOOLS AND CERTAIN OTHER ESTABLISHMENTS.. JAMA. 1907;XLVIII(12):1013-1015. doi:10.1001/jama.1907.25220380029001g