[Possible causative factors in epidemic incidence of plantar warts]

A locally increased incidence of plantar warts in schoolchildren was demonstrated statistically, although the origins and causes of the epidemic remain unclear. Excessively sweating feet rather than barefoot gymnastics in school, and perhaps the wearing of rubber boots or nylon stockings appear to facilitate the infection. The use of a public swimming pool may be a possible cause, but could not be proven. It seems that an intact, thickened, dry horny layer provides some protection whereas a softened, moistened and macerated horny layer promotes the spread of plantar warts.