All are host specific, with the only known reservoir is man. The incubation period of the virus remains unknown, yet it is estimated to be one to twenty weeks. It mostly affects children and young adults, most commonly those aged between twelve and sixteen years of age. Maceration of the skin is a predisposing factor in regard to this viral infection. In patients with Hodgkin's disease and those taking immunosuppressive agents, increased numbers of warts are seen which are extremely resistant to treatment.
Warts are contagious and more easily spread if local trauma occurs to the epidermis.
The contagiousness of the wart varies depending upon the type of wart, amount of virus it contains, and the host's susceptibility. Once infected, new warts may develop over a small area in various sites, such as the heel. Each new lesion results from initial exposure or skin associated viruses, rather than blood borne infection. As the basal cells replicate so to does the virus, it is continually transported within the cells as they migrate upwards through the varying layers of epithelium. The epidermis becomes acanthotic, as abnormal mitotic activity occurs leading to hyperplasia of the prickle cell which forms the hyperkeratotic covering of the wart.