Human papilloma virus (HPV) causes common warts, the small, white, beige or brown skin growths that can appear almost anywhere on the body and on the moist mucous membranes near the mouth, anus and genitals.
There are more than 100 different types of HPV, each with its own favorite skin surface to invade. Some cause the small, painless, rough-surfaced warts found on the fingers and face. Others cause the larger, more painful and flatter plantar warts that grow on the soles of the feet. More than 25 different types of HPV can infect the skin covering the sex organs, cervix and opening of the anus.
Genital HPV infections are very common. Up to 80 percent of sexually active adults will get an HPV infection of the genital area at some point in their lives. In most cases, these infections do not cause symptoms. They can cause genital warts
In a small number of women, certain HPV strains cause changes in the cervix that can become cancerous if not treated. HPV is also linked to cancers of the penis, vagina, anus, vulva, and also to mouth and throat cancers. HPV subtypes 16 and 18 are the causes of most cancers. HPV types 6 and 11 cause most cases of genital warts.
Human papilloma viruses usually are spread by direct skin contact, such as shaking the hand of someone who has a wart on their finger or having sexual intercourse with someone who has a genital HPV infection. Genital HPV infections can be spread by people with no symptoms, but the risk of infection is particularly high if you have intercourse with someone who has genital warts.
Less often, the viruses are carried on surfaces touched by someone who has warts, especially inside shoes that have been worn by someone with plantar warts. Once a person has been infected with an HPV, symptoms usually take three to four months to develop. However, in some cases, warts have developed as long as two years after contact with an infected person or contaminated surface.
Health experts estimate that common warts can be found on the hands of about one-fourth of all people in the United States, especially children. For some unknown reason, plantar warts are most common among teenagers and young adults.