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Week of 2.23.07

Human Papillomavirus (HPV) Facts

What is HPV?

HPV diagram
Graphic: How HPV can lead to cancer [pdf] (source: The Philadelphia Inquirer)
HPV is a group of viruses that includes more than 100 different strains or types. More than 30 of these viruses are sexually transmitted, and they can infect the genital area of men and women. HPV is one of the most common causes of sexually transmitted infection (STI) in the world.

While most people who become infected with HPV will not have any symptoms and will clear the infection on their own, some will develop complications that may lead to cancer.

How do you contract HPV?

HPV is spread through direct sexual contact or, more rarely, skin-to-skin contact during sexual acts. Genital warts, the most obvious sign of HPV infection, are very contagious. About two-thirds of people who have sexual contact with a partner with genital warts will develop warts, usually within three months of contact.

Someone infected with HPV but without symptoms can still spread the virus to sexual partners and/or develop HPV related complications.

What are the symptoms of HPV infection?

Most people who have a genital HPV infection do not know they are infected because many types of the virus remain latent and cause no symptoms.

The most easily recognized sign of genital HPV infection is genital warts, which only appear if one has contracted a specific kind of HPV and the infection is active. (However, one may spread the virus even if he or she does not have warts.) Warts may look like tiny bunches of cauliflower or like flat, white areas that may be difficult to see.

Many people have a genital HPV infection without genital warts. Some of these types of the virus are ones most associated with precancerous and cancerous changes to the cervix, making diagnosis important.

How is HPV diagnosed?

Health professionals diagnose HPV through medical history and physical examination. Women with genital warts should be examined for possible HPV infection of the cervix.

Most women are diagnosed with HPV on the basis of abnormal Pap tests. A Pap test is the primary cancer-screening tool for cervical cancer or pre-cancerous changes in the cervix, many of which are related to HPV. Thus, yearly Pap tests are an important part of diagnosis of HPV for women.

No HPV tests are available for men.

Is there a cure for HPV infection?

There is no "cure" for HPV infection. In most cases, the infection goes away on its own, although the virus remains. Available treatments are most often directed to the changes in the skin or mucous membrane caused by HPV infection, such as warts and pre-cancerous changes in the cervix.

What are the greatest risk factors for contracting HPV?

Risk factors include:
  • Having unprotected sexual or genital contact
  • Having multiple sex partners or a high-risk partner(s) who have had multiple sex partners or HPV-infected sex partners.
  • Starting sexual activity before age 18.
  • Having an impaired immune system.
How many people are infected with HPV?

Health experts estimate there are more cases of genital HPV infection than any other STI in the United States. At least 20 million people in this country are already infected. Approximately 6.2 million new cases of sexually-transmitted HPV infections are reported each year, according to the Centers for Disease Control and Prevention (CDC).

About 50 percent of sexually active men and women acquire genital HPV infection at some point in their lives. By age 50, at least 80 percent of women will have acquired genital HPV infection.

How is HPV related to cancer?

Research has determined that approximately 10 of the 30 identified genital HPV types can lead, in rare cases, to development of cervical cancer. The only known cause of cervical cancer is HPV, and the research on how it causes the cancer is solidly established.

Every year in the U.S. about 10,000 women get cervical cancer, and 3,700 die from it, according to the CDC, It is the second-leading cause of cancer deaths among women around the world. HPV is also linked to other rare cancers such as anal, vaginal and penile cancers.

How do you prevent the spread of HPV?

Someone infected with HPV should avoid direct sexual contact with others during treatment and for several weeks after treatment ends. Recently a vaccine called Gardisil was introduced by the pharmaceutical company Merck. Gardasil blocks certain high-risk strains of HPV which cause 70 percent of cervical cancers. GlaxoSmithKline also has a vaccine in development that is in the final stages of clinical testing.

How does the vaccine work?
The vaccine works like most vaccines: by stimulating an immune response that protects against infection, without actually causing infection. It is not a live virus. Like the hepatitis B vaccine, the HPV vaccine is made with a single protein from the virus that induces protective antibodies. Thus, the virus never gets to cervical cells.

How effective is the vaccine?

Gardasil prevents a vaccinated person from contracting (and thus transmitting) the four strains of HPV that cause up to 70 percent of all cervical cancers and 90 percent of genital warts. But it works only if a woman gets the vaccine before she's sexually active or has an HPV infection.

The vaccine is most effective before first sexual contact. However, according to the CDC most sexually active women will still benefit from the vaccine. For example, a woman might have a certain strain of HPV, but the vaccine could prevent her from getting another.

(Sources: Centers for Disease Control and Prevention, National Institutes of Health, WebMD)

Related Links:

» Centers for Disease Control and Prevention: Genital HPV Infection

» Information For Teens: Vaccine Against Genital Warts and Cervical Cancer