Causes
Warts can be caused by 70 different strains of HPV. These viruses exist naturally on human skin, so when a person's immune system is weak (from illness or medications) he or she is at a higher risk of contracting the virus.
Common, plantar, or plane warts can be acquired through something as simple as a cut. Walking barefoot in public areas is also a high-risk activity for contracting warts. Genital warts are more serious and also the most contagious. They are transmitted through direct sexual contact and may take from 1 to 24 months to appear.