Ans. The human papillomavirus (HPV) is the primary cause of warts. The virus leads to an overproduction of the hard protein keratin in the epidermis, the top layer of skin. The additional keratin gives warts their rough, hard texture. Warts aren't considered particularly contagious but can spread through close skin-to-skin contact. Additionally, the infection may spread covertly from contaminated objects or surfaces, such as the vicinity of a swimming pool. If your skin is damaged or wet, you run a higher risk of contracting an infection. A wart or verruca may not show up for weeks or even months after you become infected.