Human papillomavirus (HPV) is a group of viruses that may cause common skin warts (papillomas). Some types of HPV are sexually transmitted. Of those types, there are two categories:

• Low risk. This type of HPV can cause genital warts in some people, although most people do not get warts. Therefore, most people with low risk types of HPV do not know they are infected. Warts can form weeks, months or years after sexual contact with a person infected with HPV. Genital warts are most commonly associated with HPV-6 and HPV-11. Low risk HPVs do not cause precancerous changes on the cervix.
  
  
• High risk. This type of HPV can cause changes that may lead to precancerous changes in the cervix, penis or anus if untreated. High risk HPV types often cause no health problems and disappear on their own. High risk types that persist, however, are a major risk factor for cervical cancer. Sexually transmitted, high-risk HPVs include those known as HPV types 16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, 59, 68, 69 and possibly a few others.
  
  
• Warts on the hands, feet or other parts of the body (apart from genitals) are not linked to cancer.