What Causes HPV in Humans: Information on a Common Sexually Transmitted Infection

Categories : Womens sexual health
Tags : Womens health

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What Is HPV?

HPV is human papilloma virus, a group of more than 100 DNA viruses that can cause common warts, genital warts, or cervical cancer, but usually disappears without the victim any the wiser. At least half of all sexually active people will have genital HPV in their lifetimes, and at any given time 20 to 40 million Americans are infected with HPV, according to Rutgers University. The majority of HPV infections go undetected because they seldom produce symptoms. Dr. Joel McIntosh of Johns Hopkins University notes that until the 1990s, the only way to detect cervical HPV was by microscopically examining cells scraped from the cervix in a Pap test. Different HPVs target different parts of the skin and mucous membranes; for example, some infect the skin of hands and feet, some the inside of the mouth and throat, and some the genitalia.

HPV Transmission

HPV is transmitted during sexual activity, through direct skin-to-skin contact. It is spread between heterosexual partners and same-sex partners. Vaginal intercourse and anal intercourse are the most high-risk sexual activities, but any skin-to-skin contact, including oral sex, can transmit the virus. Though the virus does not survive long outside the human body, it can also be spread by sex toys. Condoms can decrease the likelihood of infection, but may not completely cover all skin areas infected by HPV.

High-Risk and Low-Risk HPV

HPV viruses can be classified as high risk and low risk. About 40 types of HPV infect the genital tract. Low-risk types of HPV can lead to genital warts or cervical changes visible on Pap smear, though the changes are often harmless and relatively short-lived. Only about 13 to 16 types are high-risk and may lead to cancer over a long period of time. Two types of HPV cause 90 percent of all genital warts and two other types cause 70 percent of all cervical cancers. Other types of HPV are linked to less common cancers such as anal cancer. But having a high-risk HPV type is not the same as having cancer. A high-risk HPV can cause cancer over time, but it is not cancer in and of itself.

HPV and the Immune System

Though HPV is the most widespread sexually transmitted infection in the world, unless you have a visible physical manifestation, such as warts, you may not even know you are infected. A healthy immune system will fight off most HPV infections, usually within 4 months to 2 years, with the average time from infection to cure about 8 months. However, if you are immunosuppressed by HIV, or in some other way, you will be more susceptible to cancer-inducing HPV types.

HPV and Cancer

Only a small minority of HPV infections in healthy people actually progress to cancer. When high-risk HPV infection persists over an extended period time, it may lead to pre-cancerous changes in the cells. Though a high-risk HPV type is a necessary component of cervical cancer, by itself, HPV is generally not enough to cause cancer. Usually, other factors are present, such as a suppressed immune system or a smoking habit. Less commonly, HPV can lead to cancer of the vulva, vagina, penis, anus, tongue, tonsils and throat.

HPV Prevention

Vaccines for both men and women are available to protect against the most common HPV infections. Gardasil will protect men and women against genital warts. It is available for boys and men ages 9 to 26 and girls and women ages 13 to 26. Both Gardasil and Cervarix will also protect women against the types of HPV that cause most cervical cancers. Women who have not had the vaccines should continue with regularly scheduled Pap tests to detect cervical changes. Though condoms can decrease the chance of HPV infection, they may not fully protect against it. Careful consideration of your sexual activity can also lower your chance of HPV infection. Remain monogamous or limit your number of partners. Choose a partner who has had few or no other prior partners. Remember that even with precautions, sexually active adults have a 75 percent chance of acquiring HPV infection in their lifetimes.