On the epidemiology of yaws in African miners (1942).

Several points of interest arise from these unusual human yaws infections: (i) European miners contracted a treponemal infection from Africans with yaws and developed yaws; (ii) the infectious patients who started the minor epidemics in the outbreaks must have been relapses from prolonged latent early infections; (iii) the time taken for the treponemes, possibly only a few minutes, to penetrate the skin through a minor injury seemed to be less than six hours; (iv) transmission occurred only at the working rock face deep underground with a tropical climate, and not on the surface 1,630 metres above sea-level, where there were abundant opportunities; (v) the search for treponemes in the environment of the working place was restricted by the inability to culture the treponeme.