Warts are caused by the human papillomavirus (HPV). There are more than 100 types of HPV, and different types of the virus cause different types of warts. Most types of HPV cause relatively harmless conditions such as common warts, while others may cause serious disease such as cancer of the cervix.

Wart viruses pass from person to person. You can also get the wart virus indirectly by touching a towel or object used by someone who has the virus. Each person's immune system responds to the HPV virus differently, so not everyone who comes in contact with HPV develops warts.

If you have warts, you can spread the virus to other places on your own body. Warts usually spread through breaks in your skin, such as a hangnail or scrape. Biting your nails also can cause warts to spread on your fingertips and around your nails.

Apr. 13, 2012