Dr. Sjoerd C. Bruggink, Dr. Just A.H. Eekhof and colleagues of the Department of Public Health and Primary Care, Leiden University Medical Center in Leiden, Netherlands, said warts are caused by infection with human papillomavirus, which is transmitted by direct contact with contaminated skin or indirectly via objects that carry the virus.
To avoid transmitting the virus, public health recommendations are often issued to wear flip-flops in communal showers and to cover warts with waterproof bandages while swimming.
The study authors inspected the hands and feet of grade-school children in three schools in the Netherlands for the presence of warts, and again a year later.
Researchers asked their parents if other family members had warts, whether the child walked barefoot at home, went to public swimming pools, used public showers and practiced sports barefoot.
The research team also collected data on classmates and close friends who had warts.
The study, published in the journal Pediatrics, found children whose family members or classmates had warts were at higher risk of developing warts, but the use of public pools or showers was not a significant risk factor.
Bruggink and colleagues concluded health recommendations should shift toward reducing transmission among families and school classes, rather than in public settings. For example, covering warts at home would potentially prevent transmission more effectively than covering warts at the swimming pool.