Questions & Answers

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What is HPV?
Human papillomavirus (HPV) is the name of a group of viruses that includes more than 100 different types. More than 30 of these viruses are sexually transmitted, and they can infect the genital area of men and women including the skin of the penis, vulva, or anus, and the lining of the vagina, cervix, or rectum.

Some of these viruses are called "high-risk" types; they may cause abnormal Pap tests and can also lead to cancer of the cervix, vulva, vagina, anus, or penis. Others are called "low-risk" types; they may cause mild Pap test abnormalities or genital warts.

How common is HPV in the United States?
HPV is the most common sexually-transmitted infection in the United States. Approximately 20 million people are currently infected with HPV. At least 50% of sexually active men and women acquire genital HPV infection at some point in their lives. By age 50, at least 80% of women will have acquired genital HPV infection. About 6.2 million Americans get a new genital HPV infection each year.

How does HPV spread?
HPV is spread through sexual contact. Most infected persons have no symptoms and are unaware they are infected and can unintentionally transmit the virus to a sex partner. Rarely, a pregnant woman passes HPV to her baby during vaginal delivery.

What are the symptoms of HPV?
Most people who become infected with HPV have no symptoms. Some people get visible genital warts, or have pre-cancerous changes in the cervix, vulva, anus, or penis.

Genital warts usually appear as soft, moist, pink, or flesh-colored swellings, usually in the genital area. They can be raised or flat, single or multiple, small or large, and sometimes cauliflower shaped. They can appear on the vulva, in or around the vagina or anus, on the cervix, and on the penis, scrotum, groin, or thigh. After sexual contact with an infected person, warts may appear within weeks or months, or not at all.

How serious is HPV?
Most HPV infections don't cause any symptoms and eventually go away, as the body's own defense system clears the virus. Women with temporary HPV infections may develop mild Pap test abnormalities that go away with time.

About 10% of women infected with HPV develop persistent HPV infection. Women with persistent high-risk HPV infections are at greatest risk for developing cervical cancer precursor lesions (abnormal cells on the lining of the cervix) and cervical cancer. (See next question.)

What are possible complications from HPV?
Cervical cancer in women is the most serious possible complication from HPV infection. Persistent infection with high-risk types of HPV is associated with almost all cervical cancers. Every year in the United States, about 10,000 women get cervical cancer and 3,700 die from it. Worldwide, cervical cancer is the second most common cancer in women; it is estimated to cause over 470,000 new cases and 233,000 deaths each year.

Persistent infection with high-risk types of HPV is also associated with cancers of the vulva, vagina, penis, and anus. However, these cancers are much less common than cervical cancer. The American Cancer Society estimates that about 1,530 men were diagnosed with penile cancer and 1,910 men were diagnosed with anal cancer in the U.S. in 2006. The risk for anal cancer is 17 times higher among gay and bisexual men than among heterosexual men. The risk is also higher among men with compromised immune systems, including those with HIV.

Genital HPV infection with low-risk types of HPV is associated with genital warts in men and women. About 1% of sexually active adults in the U.S. have visible genital warts at any point in time.

Occasionally, low-risk HPV infections can be transmitted during birth, resulting in respiratory tract warts in infants and children.

How is HPV infection diagnosed?
Genital warts in men and women are diagnosed by visual inspection.

Most women are diagnosed with HPV infection on the basis of abnormal Pap tests. Also, a specific test is available to detect HPV DNA in women. The test may be used in women with mild Pap test abnormalities or in women more than age 30 years at the time of Pap testing. The results of HPV DNA testing can help healthcare providers decide if further tests or treatment are necessary.

No HPV tests are available for men.

Can genital HPV infection be cured?
There is no "cure" for HPV infection, although the infection usually goes away on its own. Approximately 90% of women with HPV infection become HPV-negative within two years. However, it is possible that the virus remains in a "sleeping" state and could be reactivated years later.

There are treatments for the health problems that HPV can cause, such as genital warts, cervical cell changes, and cancers of the cervix, vulva, vagina, and anus.

Visible genital warts can be removed by medications the patient applies, or by treatments performed by a healthcare provider. No one treatment is best. Warts might return, especially in the first 3 months after treatment. It is not known whether treatment of genital warts will reduce the chance of passing the virus on to a sex partner. If left untreated, genital warts may go away, remain unchanged, or increase in size or number.

How can people reduce their risk for acquiring genital HPV infection?
The surest way to eliminate risk for genital HPV infection is to refrain from any genital contact with another individual.

For people who are sexually active, a long-term, mutually monogamous relationship with an uninfected partner is the strategy most likely to prevent future genital HPV infections. However, it is difficult to determine whether a partner who has been sexually active in the past is currently infected.

For those who are sexually active and who are not in long-term mutually monogamous relationships, reducing the number of sexual partners and choosing a partner less likely to be infected may reduce the risk of genital HPV infection. Partners less likely to be infected include those who have had no or few prior sex partners.

It is not known how much protection condoms provide against HPV, since areas that are not covered by a condom can be exposed to the virus. However, condoms may reduce the risk of genital warts and cervical cancer.

In 2006, a vaccine became available to protect females from four HPV types.

Questions and answers about HPV vaccine

Technically reviewed by the Centers for Disease Control and Prevention, May 2007