There are over one hundred different types or strains of the human papillomavirus or HPV. These viruses can cause the growth of warts or lesions in the tissues they infect. The types differ in the tissues they infect and the types of growths they can induce. Some strains of HPV increase the risk that a benign wart or growth will transform into cancer.
Common Skin and Oral Warts
Infection with HPV types 1, 2, 4, 26, 27, 29, 41 and 57 cause common warts, the rough looking warts on the hands and fingers. According to the Mayo Clinic, most people have been exposed to these types of HPV, although most never develop the warts. When entering through broken skin of the feet, types 1, 2 and 4 also cause plantar warts, hard, painful warts on the soles of the feet. Yet another group of HPV types, including types 3, 10, 27, 28, 41 and 49 can cause flat warts, darker than normal skin color, on the knees, hands, wrists or elbows, and face or neck. HPV types 6, 11, 16 18 and 30 can cause lesions in the mouth, nose and throat.
Epidermodysplasia Verruciformis
Patients with this rare condition, which is often hereditary, are unusually susceptible to HPV infections. They first develop small solid bumps or white spots on the hands or forearms, legs, face or trunk, surrounded by red scaly patches, after exposure to HPV types 5, 8, 9, 12, 14, 15, 17, 19, 25, 36, 38, 47, and 50, according to the Atlas of Genetics and Oncology. After decades, lesions associated with HPV types 5, 8 and 14 can become cancerous, with types 5 and 8 accounting for 90 percent of the cases.
Genital Warts
The National Cancer Institute says that there are over 30 types of HPV that spread through sexual contact, causing genital warts. Warts can be flat, or cauliflower-like bumps or small growths on a stalk, on the vulva and in the cervix or vagina of women, on the penis or scrotum of men, and around the anus of either sex. The Mayo Clinic says that HPV types 6 and 11 most commonly cause genital warts. Other HPV types causing genital warts include types 16, 18, 26, 31, 33, 35, 39, 40, 42 through 45, 51 through 54, 56, 58, 59, 66, 68, 69, 70, 71, 73, 74 and 82, according to a study in the December 2009 issue of “Infectious Diseases in Obstetrics and Gynecology”.
“High Risk” Types
Usually the body naturally eliminates an HPV infection, but in cases where a genital infection with particular strains of HPV lingers for two or more years, women can develop cervical cancer. These “high-risk” strains of HPV that are more likely to cause cervical cancer include HPV-16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, 59, 66, 68, and 73. According to the National Cancer Institute, HPV-16 and HPV-18 together cause over 70 percent of all cases of cervical cancer.
References
- Mayo Clinic.com: HPV Infection
- EMed TV: Types of HPV
- Atlas of Genetics and Oncology: Epidermodysplasia verruciformis
- National Cancer Institute: Human Papillomaviruses and Cancer
- “Infectious Diseases in Obstetrics and Gynecology”; Paola Menegazzi et al.; Human papillomavirus type distribution and correlation with cyto-histological patterns in women from the south of Italy; December 2009.
