Human papilloma virus, or HPV, is an umbrella term for more than 100 infectious viruses whose effects range from asymptomatic and benign to potentially fatal. Infection with HPV can cause papillomas, or warts, in people of all ages. The American Cancer Society notes that approximately 60 types of HPV can cause common warts which appear on the skin in areas such as the hands and feet. Other HPV types can cause warts in the genital or anal areas. Some types of HPV can cause cancer.
Types Causing Common Warts
Scientists identify the different HPV subtypes by giving them a unique identifying number. The Merck Manual notes that HPV types 1, 2 and 4 are some of the types that cause common warts, or verrucae vulgaris. Types 3, 28 and 49 can cause smooth yellow-brown warts known as flat warts. These may appear on the face or in the area of scratch marks. HPV type 7 causes lesions known as meat-handler's warts or Butcher's warts because they appear on people who handle meat on a regular basis. Types 13 and 32 can cause a rare type of wart that appears in the mouth and on the lips, an infection referred to as Heck's disease or focal epithelial hyperplasia.
Types Causing Genital Warts
A group of approximately 40 HPV types can cause infections in the genital area. The American Cancer Society points out that these types grow in the mucous membranes, the moist layers that line body cavities. The genital and anal areas of the body contain mucous membranes, and can be infected by these mucosal types of HPV.
The Centers for Disease Control and Prevention notes that some genital HPV types are classified as low-risk or non-oncogenic types, and that some are classified as oncogenic or cancer-causing types. The Merck Manual notes that Human Papillomavirus types 6 and 11 cause more than 90 percent of genital warts. Types 40, 44 and 72 can also cause genital warts.
Types Causing Cancer
One group of HPV can cause cervical cancer and other genital cancers in women, and cancers of the penis and anus in men, warns the National Institutes of Health. These high risk HPV types infect the mucous membranes in the ano-genital regions and can be associated with several invasive cancers. They may, however, resolve or disappear without any treatment in patients with healthy immune systems.
A 2003 article in the "New England Journal of Medicine" noted that the pooled results of 11 studies carried out in nine countries showed that the five most common types of HPV associated with cervical cancer were types 16, 18, 45, 31 and 33.
References
- American Cancer Society: Human Papilloma Virus (HPV), Cancer, and HPV Vaccines
- The Merck Manuals: Warts
- The Merck Manuals: Genital Warts
- Centers for Disease Control and Prevention: HPV Common Infection Common Reality
- "The New England Journal of Medicine"; Epidemiologic Classification of Human Papillomavirus Types; Nubia Muñoz, et al.: February 2003
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