Verrucae are actually caused by the HPV virus (Human Papillomavirus) and can be spread to others through contact with surfaces that may have been contaminated.
The verruca HPV virus can contaminate a floor surface, only to be picked up by another person as they walk by. For example, hotel bathrooms, gyms, showers, or even buying shoes barefoot. Children are potentially at risk as they change together several times each week for sport etc, but any age can be infected.