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 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. Some types of HPV can cause warts (such as genital or plantar warts) and others can cause 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, and approximately 3 to 9 million Canadians are infected with HPV.
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:
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.
HPV enters the body, usually through a break in the skin, and then infects the cells in the layers of the skin. The virus then replicates or multiplies in the body. The time between first contracting HPV and the appearance of lesions can be weeks to months or even years. Many people don't even know they are infected with HPV.
HPV is transmitted by skin-to-skin contact. HPV infections that cause skin warts (e.g., plantar or common warts) can be acquired through a cut, but the risk of transmission is low. Walking barefoot in public areas such as the gym or pool can be a risk for infection with the types of HPV that cause plantar warts.
HPV infections that cause genital warts are very contagious and are usually contracted through sexual activity with an infected person. This includes kissing or touching the skin of the infected areas (e.g., scrotum, vagina, vulva, anus) and having intercourse. Although HPV is more likely to be transmitted when lesions or warts are visible, transmission is possible even without the presence of visible warts.
A mother with a genital HPV infection may also transmit the virus to the infant during labour.
The risk factors for HPV infection include:
Most HPV infections go unnoticed because they don't cause any symptoms. The virus may have been contracted years ago and it can remain in the body for weeks, years, or even a lifetime without showing any symptoms of an infection.
For those who experience symptoms, the type of symptoms depends on the type of HPV infection.