The human papillomavirus (HPV) is a virus that causes skin and mucous membrane (the moist lining of body cavities such as the mouth and nose that connect with the outside of the body) infections. It is usually passed from one person to another by skin-to-skin contact, including sexual contact.
There are more than 100 types of HPV that can affect different parts of the body, about 40 of which are transmitted through sexual contact. Some types of HPV can cause warts (such as genital or plantar warts) and others can lead to cancer (such as cervical or anal cancer).
HPV infection is one of the most common sexually transmitted infections (STIs) in Canada and around the world. At least 70% of sexually active men and women will have at least one HPV infection in their lifetime.
The different HPV types are classified into low and high risk based on their association with cancer. "Low risk" types rarely cause cancer. "High risk" types have a greater likelihood of causing cancer but they do not necessarily lead to cancer. These various types can cause different conditions, including:
- skin warts: These infections are also known as common, plantar, or flat warts and are caused by low-risk types. The warts can appear on your arms, face, feet, hands, and legs. They can develop at any age but are most common in children.
- genital warts: HPV types 6 and 11 cause about 90% of genital warts and are low-risk types.
- cervical dysplasia: HPV can cause lesions of abnormal cells called cervical dysplasia in a woman's cervix. These lesions are considered to be precancerous (they are not cancerous cells, but they may develop into cancer cells later). The HPV infection often resolves and clears on its own, but cervical dysplasia should be treated because it can lead to cervical cancer.
- cervical cancer: The high-risk HPV types 16 and 18 cause about 70% of all cervical cancers. Other high risk types are 31, 33, 45, 52 and 58, which causes about 20% of cervical cancers. These high risk types have also been linked to penile and anal cancers.
HPV can cause infections and lesions in other areas of the body, such as in the upper respiratory tract.
The majority of HPV infections are generally harmless, though they can be embarrassing. However, the HPV infections that can lead to cervical cancer and other types of cancers are a concern.